Update pylint.yml

Update deprecated actions/checkout@v2 to v3

Author: rbaltrusch

.github/workflows/pylint.yml

@@ -9,7 +9,7 @@ jobs:
       matrix:
         python-version: ["3.8", "3.9"]
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v3
     - name: Set up Python ${{ matrix.python-version }}
       uses: actions/setup-python@v2
       with: