Bump actions/cache from v1 to v2.1.0

Bumps [actions/cache](https://github.com/actions/cache) from v1 to v2.1.0.
- [Release notes](https://github.com/actions/cache/releases)
- [Commits](actions/cache@v1...d29c1df)

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

.github/workflows/maven.yml

@@ -35,7 +35,7 @@ jobs:
         uses: actions/checkout@v2
 
       - name: Set up cache for ~./m2/repository
-        uses: actions/cache@v1
+        uses: actions/cache@v2.1.0
         with:
           path: ~/.m2/repository
           key: maven-${{ matrix.os }}-java${{ matrix.java }}-${{ hashFiles('**/pom.xml') }}