Bump actions/cache from 2.1.5 to 2.1.6 (#7278)

Bumps [actions/cache](https://github.com/actions/cache) from 2.1.5 to 2.1.6.
- [Release notes](https://github.com/actions/cache/releases)
- [Commits](actions/cache@v2.1.5...v2.1.6)

Signed-off-by: dependabot[bot] <[email protected]>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

.github/workflows/gradle_branch.yml

@@ -19,7 +19,7 @@ jobs:
         distribution: 'adopt'
         java-version: '8'
     - name: Cache Gradle packages
-      uses: actions/[email protected].5
+      uses: actions/[email protected].6
       with:
         path: ~/.gradle/caches
         key: ${{ runner.os }}-gradle-${{ secrets.CACHE_VERSION }}-${{ hashFiles('**/*.gradle') }}

.github/workflows/gradle_jdk11.yml

@@ -21,7 +21,7 @@ jobs:
         distribution: 'adopt'
         java-version: '11'
     - name: Cache Gradle packages
-      uses: actions/[email protected].5
+      uses: actions/[email protected].6
       with:
         path: ~/.gradle/caches
         key: ${{ runner.os }}-gradle-1-${{ hashFiles('**/*.gradle') }}

.github/workflows/gradle_pr.yml

@@ -19,7 +19,7 @@ jobs:
         distribution: 'adopt'
         java-version: '8'
     - name: Cache Gradle packages
-      uses: actions/[email protected].5
+      uses: actions/[email protected].6
       with:
         path: ~/.gradle/caches
         key: ${{ runner.os }}-gradle-1-${{ hashFiles('**/*.gradle') }}

.github/workflows/gradle_release.yml

@@ -24,7 +24,7 @@ jobs:
         distribution: 'adopt'
         java-version: '8'
     - name: Cache Gradle packages
-      uses: actions/[email protected].5
+      uses: actions/[email protected].6
       with:
         path: ~/.gradle/caches
         key: ${{ runner.os }}-gradle-${{ secrets.CACHE_VERSION }}-${{ hashFiles('**/*.gradle') }}

.github/workflows/gradle_snapshot.yml

@@ -22,7 +22,7 @@ jobs:
         distribution: 'adopt'
         java-version: '8'
     - name: Cache Gradle packages
-      uses: actions/[email protected].5
+      uses: actions/[email protected].6
       with:
         path: ~/.gradle/caches
         key: ${{ runner.os }}-gradle-${{ secrets.CACHE_VERSION }}-${{ hashFiles('**/*.gradle') }}