Move ext-soap to suggestions

Author: tvdijen

composer.json

@@ -16,7 +16,6 @@
         "ext-libxml": "*",
         "ext-openssl": "*",
         "ext-pcre": "*",
-        "ext-soap": "*",
         "ext-zlib": "*",
 
         "nyholm/psr7": "^1.8",
@@ -34,6 +33,9 @@
         "simplesamlphp/simplesamlphp-test-framework": "^1.5",
         "icanhazstring/composer-unused": "^0.9.3"
     },
+    "suggest": {
+        "ext-soap": "*"
+    },
     "autoload": {
         "psr-4": {
             "SimpleSAML\\SAML2\\": "src/"