Update 5.1 conformance tests with memoryview and euler, improve conformance output

- Enable memoryview() tests in 5.1 conformance (Python 3.13 supports __buffer__)
- Add test_mathutils_euler.py for 5.1 conformance
- Show Python version in conformance check output

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

main.py

@@ -433,7 +433,6 @@ def conformance_check(versions: list[str] | None = None) -> None:
     for version in versions:
         version_dir = dist_dir / version
         test_dir = conformance_dir / version
-        print(f"=== Conformance check against Blender {version} stubs ===")
 
         python_version_file = version_dir / ".python-version"
         python_version = (
@@ -442,6 +441,10 @@ def conformance_check(versions: list[str] | None = None) -> None:
             else "3.11"
         )
 
+        print(
+            f"=== Conformance check against Blender {version} stubs with Python {python_version} ==="
+        )
+
         config = version_dir / "pyrightconfig.conformance.json"
         config.write_text(
             json.dumps(