disable Mono on GitHub Actions osx-arm64 runner image

Author: smdn

tests/TargetFrameworks.props

@@ -37,4 +37,18 @@ SPDX-License-Identifier: MIT
     <!-- disable Mono on GitHub Actions Ubuntu 24.04 runner images -->
     <EnableTargetFrameworkNetFx Condition=" '$(GITHUB_ACTIONS)' == 'true' ">false</EnableTargetFrameworkNetFx>
   </PropertyGroup>
+
+  <!-- On MacOS (arm64) -->
+  <PropertyGroup
+    Condition="
+      $([System.Runtime.InteropServices.RuntimeInformation]::RuntimeIdentifier.StartsWith('osx-arm64')) or
+      (
+        $([System.OperatingSystem]::IsMacOS()) and
+        $([System.Runtime.InteropServices.RuntimeInformation]::OSArchitecture.StartsWith('Arm64'))
+      )
+    "
+  >
+    <!-- disable Mono on GitHub Actions osx-arm64 runner images -->
+    <EnableTargetFrameworkNetFx Condition=" '$(GITHUB_ACTIONS)' == 'true' ">false</EnableTargetFrameworkNetFx>
+  </PropertyGroup>
 </Project>