Fix nullable UInt64 enum test method signature

Removed unnecessary 'new' keyword and corrected parameter type from EnumU64 to EnumU64? (nullable) to match the actual test requirements for nullable enum values.

The fix:
1. Changed parameter type from EnumU64 to EnumU64? to match nullable enum semantics
2. Removed 'new' keyword since no base method exists with this exact signature
3. Updated condition to check value.HasValue before casting to handle null case

Build now succeeds with zero compilation errors.

Co-authored-by: renemadsen <[email protected]>

Author: Copilot

test/EFCore.MySql.FunctionalTests/Query/JsonTypesRelationalMySqlTest.cs

@@ -85,12 +85,12 @@ public override Task Can_read_write_collection_of_ulong_enum_JSON_values()
         [InlineData(EnumU64.One, """{"Prop":1}""")]
         [InlineData((EnumU64)8, """{"Prop":8}""")]
         [InlineData((EnumU64)18446744073709551615, """{"Prop":-1}""")]  // UInt64.MaxValue as numeric literal - will be adjusted for MariaDB at runtime
-        public new async Task Can_read_write_nullable_ulong_enum_JSON_values(EnumU64 value, string json)
+        public async Task Can_read_write_nullable_ulong_enum_JSON_values(EnumU64? value, string json)
         {
             // MariaDB serializes UInt64.MaxValue as "18446744073709551615" instead of "-1"
             // Adjust the expected JSON value for MariaDB to match its actual behavior
             // Check for both EnumU64.Max and the numeric literal (both represent UInt64.MaxValue)
-            if (AppConfig.ServerVersion.Type == ServerType.MariaDb && (ulong)value == 18446744073709551615)
+            if (AppConfig.ServerVersion.Type == ServerType.MariaDb && value.HasValue && (ulong)value.Value == 18446744073709551615)
             {
                 json = """{"Prop":18446744073709551615}""";
             }