✅ Use Python 3.9 for CI

.github/workflows/test-builds.yml

@@ -144,7 +144,7 @@ jobs:
     steps:
 
     - name: Check out the PR
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
 
     - name: Cache pip
       uses: actions/cache@v3
@@ -160,11 +160,11 @@ jobs:
         path: ~/.platformio
         key: ${{ runner.os }}-${{ hashFiles('**/lockfiles') }}
 
-    - name: Select Python 3.7
-      uses: actions/setup-python@v3
+    - name: Select Python 3.9
+      uses: actions/setup-python@v4
       with:
-        python-version: '3.7' # Version range or exact version of a Python version to use, using semvers version range syntax.
-        architecture: 'x64' # optional x64 or x86. Defaults to x64 if not specified
+        python-version: '3.9'
+        architecture: 'x64'
 
     - name: Install PlatformIO
       run: |