bump setup-python version

Author: DanielGoldfarb

.github/workflows/mplfinance_checks.yml

@@ -27,7 +27,7 @@ jobs:
       - run: echo "The ${{ github.repository }} repository has been cloned to the runner."
 
       - name: Set up Python ${{ matrix.python-version }}
-        uses: actions/setup-python@v2
+        uses: actions/setup-python@v4
         with:
           python-version: ${{ matrix.python-version }}