Add earlier Python version syntax check for __pip-runner__.py

Author: notatallshaw

pyproject.toml

@@ -272,6 +272,11 @@ max-branches = 28  # default is 12
 max-returns = 13  # default is 6
 max-statements = 134  # default is 50
 
+[tool.ruff.per-file-target-version]
+# `__pip-runner__.py` should be Python 2.7 compatible but the
+# earliest version of Python ruff will check is 3.7
+"src/pip/__pip-runner__.py" = "py37"
+
 ######################################################################################
 # mypy
 #