not install pytest & black in github action

.github/workflows/main.yml

@@ -27,19 +27,17 @@ jobs:
           restore-keys: |
             ${{ runner.os }}-pip-
 
-      - name: Test formatting
-        run: |
-          pip install black
-          black --check .
-
       - name: Install dependencies
         run: |
           python -m pip install --upgrade pip
           pip install -r requirements.txt
 
+      - name: Test formatting
+        run: |
+          black --check .
+
       - name: Test with pytest
         run: |
-          pip install pytest
           pytest
 
       - name: Publish to Docker Registry