Bump actions/cache from 2.1.5 to 2.1.6

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]>

Author: dependabot[bot]

.github/workflows/maven.yml

@@ -37,7 +37,7 @@ jobs:
           distribution: 'adopt'
           java-version: ${{ matrix.java }}
       - name: Cache local Maven repository
-        uses: actions/[email protected].5
+        uses: actions/[email protected].6
         with:
           path: ~/.m2/repository
           key: ${{ runner.os }}-maven-${{ hashFiles('**/pom.xml') }}
@@ -83,7 +83,7 @@ jobs:
           distribution: 'adopt'
           java-version: 11.0.x
       - name: Cache local Maven repository
-        uses: actions/[email protected].5
+        uses: actions/[email protected].6
         with:
           path: ~/.m2/repository
           key: ${{ runner.os }}-maven-${{ hashFiles('**/pom.xml') }}