Upgrade Core to 45a8ba75a1e3037896bac1ff6885f344402bf857 (#776)

Signed-off-by: Juan Cruz Viotti <jv@jviotti.com>

Author: jviotti

DEPENDENCIES

@@ -1,3 +1,3 @@
 vendorpull https://github.com/sourcemeta/vendorpull 1dcbac42809cf87cb5b045106b863e17ad84ba02
-core https://github.com/sourcemeta/core 7534bfe0108824e8f84de77a270f7d0bdd667819
+core https://github.com/sourcemeta/core 45a8ba75a1e3037896bac1ff6885f344402bf857
 jsonschema-test-suite https://github.com/json-schema-org/JSON-Schema-Test-Suite c7257e92580678a086f0b9243a1903ed88bd27f7

test/alterschema/alterschema_lint_draft3_test.cc

@@ -1281,7 +1281,7 @@ TEST(AlterSchema_lint_draft3, unknown_keywords_prefix_9) {
   const sourcemeta::core::JSON expected = sourcemeta::core::parse_json(R"JSON({
     "$schema": "http://json-schema.org/draft-03/schema#",
     "type": "object",
-    "x-definitions": {
+    "definitions": {
       "MyType": {
         "type": "string"
       }