Remove dependency on ext-xml

PHPUnit is not actually using the ext-xml extension. Its own test suite passes
for a minimal PHP 8.5 build with the following configure line:

    ./configure --disable-all --enable-option-checking=fatal --enable-werror --enable-ctype --enable-tokenizer --enable-mbstring --enable-dom --with-libxml --enable-xmlwriter --enable-phar --enable-filter

with the following extensions loaded

    [PHP Modules]
    Core
    ctype
    date
    dom
    filter
    hash
    json
    lexbor
    libxml
    mbstring
    pcre
    Phar
    random
    Reflection
    SPL
    standard
    tokenizer
    uri
    xmlwriter
    Zend OPcache

    [Zend Modules]
    Zend OPcache

(cherry picked from commit 7848d0b)

Author: TimWolla

.github/workflows/ci.yaml

@@ -64,7 +64,7 @@ jobs:
         uses: shivammathur/setup-php@f3e473d116dcccaddc5834248c87452386958240 # 2.37.2
         with:
           php-version: ${{ env.PHP_VERSION }}
-          extensions: none, curl, dom, json, libxml, mbstring, openssl, phar, soap, tokenizer, xml, xmlwriter
+          extensions: none, curl, dom, json, libxml, mbstring, openssl, phar, soap, tokenizer, xmlwriter
           coverage: none
           tools: none
 
@@ -176,7 +176,7 @@ jobs:
         uses: shivammathur/setup-php@f3e473d116dcccaddc5834248c87452386958240 # 2.37.2
         with:
           php-version: 8.3
-          extensions: none, ctype, curl, date, dom, json, libxml, mbstring, phar, simplexml, soap, tokenizer, xml, xmlwriter, zlib
+          extensions: none, ctype, curl, date, dom, json, libxml, mbstring, phar, simplexml, soap, tokenizer, xmlwriter, zlib
           coverage: none
           tools: none
 
@@ -212,7 +212,7 @@ jobs:
     timeout-minutes: 10
 
     env:
-      PHP_EXTENSIONS: none, curl, dom, json, libxml, mbstring, openssl, phar, soap, tokenizer, xml, xmlwriter
+      PHP_EXTENSIONS: none, curl, dom, json, libxml, mbstring, openssl, phar, soap, tokenizer, xmlwriter
       PHP_INI_VALUES: assert.exception=1, zend.assertions=1, error_reporting=-1, log_errors_max_len=0, display_errors=On
 
     strategy:
@@ -299,7 +299,7 @@ jobs:
     timeout-minutes: 10
 
     env:
-      PHP_EXTENSIONS: none, curl, dom, json, libxml, mbstring, openssl, phar, soap, tokenizer, xml, xmlwriter
+      PHP_EXTENSIONS: none, curl, dom, json, libxml, mbstring, openssl, phar, soap, tokenizer, xmlwriter
       PHP_INI_VALUES: assert.exception=1, zend.assertions=1, error_reporting=-1, log_errors_max_len=0, display_errors=On
 
     strategy:
@@ -414,7 +414,7 @@ jobs:
         with:
           php-version: 7.4
           coverage: xdebug
-          extensions: none, curl, dom, json, libxml, mbstring, phar, soap, tokenizer, xml, xmlwriter
+          extensions: none, curl, dom, json, libxml, mbstring, phar, soap, tokenizer, xmlwriter
           ini-values: assert.exception=1, zend.assertions=1, error_reporting=-1, log_errors_max_len=0, display_errors=On
           tools: none
 
@@ -465,7 +465,7 @@ jobs:
     timeout-minutes: 10
 
     env:
-      PHP_EXTENSIONS: none, dom, json, fileinfo, iconv, libxml, mbstring, phar, soap, tokenizer, xml, xmlwriter
+      PHP_EXTENSIONS: none, dom, json, fileinfo, iconv, libxml, mbstring, phar, soap, tokenizer, xmlwriter
       PHP_INI_VALUES: assert.exception=1, phar.readonly=0, zend.assertions=1
 
     steps:
@@ -528,7 +528,7 @@ jobs:
     timeout-minutes: 10
 
     env:
-      PHP_EXTENSIONS: none, curl, dom, json, fileinfo, iconv, libxml, mbstring, phar, soap, tokenizer, xml, xmlwriter
+      PHP_EXTENSIONS: none, curl, dom, json, fileinfo, iconv, libxml, mbstring, phar, soap, tokenizer, xmlwriter
       PHP_INI_VALUES: assert.exception=1, phar.readonly=0, zend.assertions=1
 
     strategy:
@@ -604,7 +604,7 @@ jobs:
     timeout-minutes: 10
 
     env:
-      PHP_EXTENSIONS: none, curl, dom, json, fileinfo, iconv, libxml, mbstring, phar, soap, tokenizer, xml, xmlwriter
+      PHP_EXTENSIONS: none, curl, dom, json, fileinfo, iconv, libxml, mbstring, phar, soap, tokenizer, xmlwriter
       PHP_INI_VALUES: assert.exception=1, phar.readonly=0, zend.assertions=1
 
     strategy:

build/templates/binary-phar-autoload.php.in

@@ -30,7 +30,7 @@ if (version_compare('7.2.0', PHP_VERSION, '>')) {
     die(1);
 }
 
-foreach (['dom', 'json', 'libxml', 'mbstring', 'tokenizer', 'xml', 'xmlwriter'] as $extension) {
+foreach (['dom', 'json', 'libxml', 'mbstring', 'tokenizer', 'xmlwriter'] as $extension) {
     if (extension_loaded($extension)) {
         continue;
     }

composer.json

@@ -33,7 +33,6 @@
         "ext-json": "*",
         "ext-libxml": "*",
         "ext-mbstring": "*",
-        "ext-xml": "*",
         "ext-xmlwriter": "*",
         "doctrine/instantiator": "^1.5.0",
         "myclabs/deep-copy": "^1.13.4",

composer.lock

@@ -38,7 +38,7 @@ if (version_compare('7.2.0', PHP_VERSION, '>')) {
     die(1);
 }
 
-foreach (['dom', 'json', 'libxml', 'mbstring', 'tokenizer', 'xml', 'xmlwriter'] as $extension) {
+foreach (['dom', 'json', 'libxml', 'mbstring', 'tokenizer', 'xmlwriter'] as $extension) {
     if (extension_loaded($extension)) {
         continue;
     }