Bump actions/cache from 2.1.4 to 2.1.6 (apache#153)

Bumps [actions/cache](https://github.com/actions/cache) from 2.1.4 to 2.1.6.
- [Release notes](https://github.com/actions/cache/releases)
- [Commits](actions/cache@v2.1.4...v2.1.6)

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

Author: dependabot[bot]

.github/workflows/maven.yml

@@ -32,7 +32,7 @@ jobs:
 
     steps:
     - uses: actions/checkout@v2.3.4
-    - uses: actions/cache@v2.1.4
+    - uses: actions/cache@v2.1.6
       with:
         path: ~/.m2/repository
         key: ${{ runner.os }}-maven-${{ hashFiles('**/pom.xml') }}