Fix CI action versions

.github/workflows/build.yml

@@ -15,12 +15,14 @@ jobs:
         restore-keys: |
           ${{ runner.os }}-pip-
     - name: Cache PlatformIO
-      uses: actions/cache@v2
+      uses: actions/cache@v3
       with:
         path: ~/.platformio
         key: ${{ runner.os }}-${{ hashFiles('**/lockfiles') }}
     - name: Set up Python
       uses: actions/setup-python@v4
+      with:
+        python-version: "3.9"
     - name: Install PlatformIO
       run: |
         python -m pip install --upgrade pip