chore: upgrade actions/checkout to v2

Author: peaceiris

.github/workflows/docker-image-ci.yml

@@ -16,31 +16,25 @@ jobs:
     runs-on: ubuntu-18.04
 
     steps:
-    - uses: actions/checkout@v1
-      with:
-        fetch-depth: 1
+    - uses: actions/checkout@v2
 
     - name: build
       env:
         DOCKER_IMAGE: docker.pkg.github.com/${{ github.repository }}/action:latest
       run: |
-        docker build . --file Dockerfile --tag ${DOCKER_IMAGE} ||
-        (echo -e "\e[31m[${GITHUB_WORKFLOW}] failed to build\e[m" && exit 1)
+        docker build . --file Dockerfile --tag ${DOCKER_IMAGE}
 
   shellcheck:
     runs-on: ubuntu-18.04
     steps:
-    - uses: actions/checkout@v1
-      with:
-        fetch-depth: 1
+    - uses: actions/checkout@v2
+
     - name: shellcheck
       run: shellcheck ./entrypoint.sh
 
   hadolint:
     runs-on: macos-latest
     steps:
-    - uses: actions/checkout@v1
-      with:
-        fetch-depth: 1
+    - uses: actions/checkout@v2
     - run: brew install hadolint
     - run: hadolint ./Dockerfile