Update actions/checkout action to v2.7.0 (#205)

Author: renovate[bot]

.github/workflows/detekt.yml

@@ -12,7 +12,7 @@ jobs:
       GRADLE_OPTS: -Dorg.gradle.daemon=false
 
     steps:
-      - uses: actions/checkout@v2.3.3
+      - uses: actions/checkout@v2.7.0
       - name: Set up JDK 11
         uses: actions/setup-java@v1
         with:

.github/workflows/diktat.yml

@@ -12,7 +12,7 @@ jobs:
       GRADLE_OPTS: -Dorg.gradle.daemon=false
 
     steps:
-      - uses: actions/checkout@v2.4.0
+      - uses: actions/checkout@v2.7.0
       - name: Set up JDK 11
         uses: actions/setup-java@v2
         with:

.github/workflows/release.yml

@@ -20,7 +20,7 @@ jobs:
         os: [ ubuntu-latest, windows-latest, macos-latest ]
     steps:
       - name: Checkout
-        uses: actions/checkout@v2.3.3
+        uses: actions/checkout@v2.7.0
         with:
           # release workflow should have access to all tags
           fetch-depth: 0