Use submodule option of actions/checkout

Author: kateinoigakukun

.github/workflows/test.yml

@@ -13,7 +13,8 @@ jobs:
     runs-on: Ubuntu-18.04
     steps:
       - uses: actions/checkout@v2
-      - run: git submodule update --init
+        with:
+          submodule: true
       - name: Setup swiftenv
         run: |
           git clone https://github.com/kylef/swiftenv.git ~/.swiftenv
@@ -34,7 +35,8 @@ jobs:
     runs-on: macOS-10.15
     steps:
       - uses: actions/checkout@v2
-      - run: git submodule update --init
+        with:
+          submodule: true
       - run: sudo xcode-select -s "${{ matrix.xcode-version }}"
       - run: swift --version
       - run: swift test
@@ -43,7 +45,8 @@ jobs:
     runs-on: macOS-10.15
     steps:
       - uses: actions/checkout@v2
-      - run: git submodule update --init
+        with:
+          submodule: true
       - run: swift test --enable-code-coverage
       - run: echo "SWIFT_CODECOV_PATH=$(swift test --show-codecov-path)" >> $GITHUB_ENV
       - uses: codecov/codecov-action@v1