Update main.yaml

Fix wrong indent

.github/workflows/main.yaml

@@ -21,10 +21,10 @@ jobs:
     steps:
     - uses: actions/checkout@v1
     - name: Set up Python
-        uses: actions/setup-python@v1
+     uses: actions/setup-python@v1
     - name: Install dependencies
-        run: |
+      run: |
         python -m pip install --upgrade pip
         pip install platformio
     - name: Run PlatformIO Tests
-      run: platformio test --environment desktop
+      run: platformio test --environment desktop