Exclude .venv from linting, in case it's under the source root

dev.py

@@ -51,7 +51,7 @@ def do_lint() -> None:
     print('>>>> Running flake8')
     pipenv = local['pipenv']
     try:
-        pipenv['run', 'python', '-m', 'flake8', '--exclude=node_modules'] & FG
+        pipenv['run', 'python', '-m', 'flake8', '--exclude=node_modules,.venv'] & FG
     except ProcessExecutionError as e:
         sys.exit(e.retcode)