build(deps): bump actions/cache from 2.1.4 to 2.1.7

Bumps [actions/cache](https://github.com/actions/cache) from 2.1.4 to 2.1.7.
- [Release notes](https://github.com/actions/cache/releases)
- [Commits](actions/cache@v2.1.4...v2.1.7)

---
updated-dependencies:
- dependency-name: actions/cache
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

.github/workflows/build.yml

@@ -175,7 +175,7 @@ jobs:
         echo "LD_LIBRARY_PATH=${GITHUB_WORKSPACE}/multissl/openssl/${OPENSSL_VER}/lib" >> $GITHUB_ENV
     - name: 'Restore OpenSSL build'
       id: cache-openssl
-      uses: actions/[email protected].4
+      uses: actions/[email protected].7
       with:
         path: ./multissl/openssl/${{ env.OPENSSL_VER }}
         key: ${{ runner.os }}-multissl-openssl-${{ env.OPENSSL_VER }}
@@ -223,7 +223,7 @@ jobs:
         echo "LD_LIBRARY_PATH=${GITHUB_WORKSPACE}/multissl/openssl/${OPENSSL_VER}/lib" >> $GITHUB_ENV
     - name: 'Restore OpenSSL build'
       id: cache-openssl
-      uses: actions/[email protected].4
+      uses: actions/[email protected].7
       with:
         path: ./multissl/openssl/${{ env.OPENSSL_VER }}
         key: ${{ runner.os }}-multissl-openssl-${{ env.OPENSSL_VER }}