Fix python version pin for lint workflow (#1885)

Using major.minor notation selects the latest patch version.

https://github.com/actions/setup-python/blob/v4/docs/advanced-usage.md#using-the-python-version-input

b/308798332

.github/workflows/lint.yaml

@@ -44,7 +44,7 @@ jobs:
       - name: Setup Python
         uses: actions/setup-python@v4
         with:
-          python-version: '^3.7.x'
+          python-version: '3.7'
       - name: Install Pip Packages
         run: pip install -r ${GITHUB_WORKSPACE}/requirements.txt
       - name: Download Resources