Re-enable flake8, pylint, mypy

Author: WardBrian

.github/workflows/main.yml

@@ -60,7 +60,7 @@ jobs:
           pip install codecov
 
       - name: Run flake8, pylint, mypy
-        if: matrix.python-version == '3.10'
+        if: matrix.python-version == '3.10.6'
         run: |
           flake8 cmdstanpy test
           pylint -v cmdstanpy test