fix(owlbot): Final correction to mypy.yml regex

Author: chalmerlowe

owlbot.py

@@ -262,8 +262,8 @@ def lint_setup_py(session):
 # Ensure mypy.yml uses the default Python version
 s.replace(
     ".github/workflows/mypy.yml",
-    r"""python-version: \["3.8"\]""",
-    """python-version: ["3.10"]""",
+    r'''python-version: "3.8"''',
+    '''python-version: "3.10"''',
 )
 
 s.shell.run(["nox", "-s", "blacken"], hide_output=False)