Fix generated_code_checks workflow step (#463)

Author: wata727

.github/workflows/generated_code_checks.yml

@@ -9,7 +9,7 @@ jobs:
     - name: Checkout
       uses: actions/checkout@v3
     - name: Checkout submodules
-    - run: git submodule update --init --depth=0
+      run: git submodule update --init --depth=0
     - name: Set up Go
       uses: actions/setup-go@v3
       with: