Removed unnecessary C# version checks in two generators

Author: Sergio0694

Microsoft.Toolkit.Mvvm.SourceGenerators/ComponentModel/ObservableValidatorValidateAllPropertiesGenerator.cs

@@ -42,12 +42,6 @@ public void Execute(GeneratorExecutionContext context)
                 return;
             }
 
-            // Validate the language version
-            if (context.ParseOptions is not CSharpParseOptions { LanguageVersion: >= LanguageVersion.CSharp9 })
-            {
-                context.ReportDiagnostic(Diagnostic.Create(UnsupportedCSharpLanguageVersionError, null));
-            }
-
             // Get the symbol for the required attributes
             INamedTypeSymbol
                 validationSymbol = context.Compilation.GetTypeByMetadataName("System.ComponentModel.DataAnnotations.ValidationAttribute")!,

Microsoft.Toolkit.Mvvm.SourceGenerators/Messaging/IMessengerRegisterAllGenerator.cs

@@ -39,12 +39,6 @@ public void Execute(GeneratorExecutionContext context)
                 return;
             }
 
-            // Validate the language version
-            if (context.ParseOptions is not CSharpParseOptions { LanguageVersion: >= LanguageVersion.CSharp9 })
-            {
-                context.ReportDiagnostic(Diagnostic.Create(UnsupportedCSharpLanguageVersionError, null));
-            }
-
             // Get the symbol for the IRecipient<T> interface type
             INamedTypeSymbol iRecipientSymbol = context.Compilation.GetTypeByMetadataName("Microsoft.Toolkit.Mvvm.Messaging.IRecipient`1")!;
 

UnitTests/UnitTests.SourceGenerators/Test_SourceGeneratorsDiagnostics.cs

@@ -319,9 +319,9 @@ public partial class SampleViewModel : ObservableValidator
                 }
             }";
 
+            // This is explicitly allowed in C# < 9.0, as it doesn't use any new features
             VerifyGeneratedDiagnostics<ObservableValidatorValidateAllPropertiesGenerator>(
-                CSharpSyntaxTree.ParseText(source, CSharpParseOptions.Default.WithLanguageVersion(LanguageVersion.CSharp7_3)),
-                "MVVMTK0013");
+                CSharpSyntaxTree.ParseText(source, CSharpParseOptions.Default.WithLanguageVersion(LanguageVersion.CSharp7_3)));
         }
 
         [TestCategory("Mvvm")]
@@ -368,9 +368,9 @@ public void Receive(MyMessage message)
                 }
             }";
 
+            // This is explicitly allowed in C# < 9.0, as it doesn't use any new features
             VerifyGeneratedDiagnostics<IMessengerRegisterAllGenerator>(
-                CSharpSyntaxTree.ParseText(source, CSharpParseOptions.Default.WithLanguageVersion(LanguageVersion.CSharp7_3)),
-                "MVVMTK0013");
+                CSharpSyntaxTree.ParseText(source, CSharpParseOptions.Default.WithLanguageVersion(LanguageVersion.CSharp7_3)));
         }
 
         /// <summary>