chore: Use actions/checkout@v2 (#6328)

.github/workflows/docker.yml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v1
+    - uses: actions/checkout@v2
     - name: Pull previous build result (for cache)
       run: docker pull misskey/misskey:latest
     - name: Build docker container

.github/workflows/nodejs.yml

@@ -28,7 +28,7 @@ jobs:
           - 6379:6379
 
     steps:
-    - uses: actions/checkout@v1
+    - uses: actions/checkout@v2
     - name: Use Node.js ${{ matrix.node-version }}
       uses: actions/setup-node@v1
       with: