build(deps): Bump actions/cache from 2.1.5 to 2.1.6 (#6504)

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](https://github.com/actions/cache/compare/v2.1.5...v2.1.6)

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

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

.github/workflows/tests.yml

@@ -28,7 +28,7 @@ jobs:
       - name: install
         run: make install install_abci
         if: "env.GIT_DIFF != ''"
-      - uses: actions/cache@v2.1.5
+      - uses: actions/cache@v2.1.6
         with:
           path: ~/go/pkg/mod
           key: ${{ runner.os }}-go-${{ hashFiles('**/go.sum') }}
@@ -36,7 +36,7 @@ jobs:
             ${{ runner.os }}-go-
         if: env.GIT_DIFF
       # Cache binaries for use by other jobs
-      - uses: actions/cache@v2.1.5
+      - uses: actions/cache@v2.1.6
         with:
           path: ~/go/bin
           key: ${{ runner.os }}-${{ github.sha }}-tm-binary
@@ -57,14 +57,14 @@ jobs:
             **/**.go
             go.mod
             go.sum
-      - uses: actions/cache@v2.1.5
+      - uses: actions/cache@v2.1.6
         with:
           path: ~/go/pkg/mod
           key: ${{ runner.os }}-go-${{ hashFiles('**/go.sum') }}
           restore-keys: |
             ${{ runner.os }}-go-
         if: env.GIT_DIFF
-      - uses: actions/cache@v2.1.5
+      - uses: actions/cache@v2.1.6
         with:
           path: ~/go/bin
           key: ${{ runner.os }}-${{ github.sha }}-tm-binary
@@ -89,14 +89,14 @@ jobs:
             **/**.go
             go.mod
             go.sum
-      - uses: actions/cache@v2.1.5
+      - uses: actions/cache@v2.1.6
         with:
           path: ~/go/pkg/mod
           key: ${{ runner.os }}-go-${{ hashFiles('**/go.sum') }}
           restore-keys: |
             ${{ runner.os }}-go-
         if: env.GIT_DIFF
-      - uses: actions/cache@v2.1.5
+      - uses: actions/cache@v2.1.6
         with:
           path: ~/go/bin
           key: ${{ runner.os }}-${{ github.sha }}-tm-binary
@@ -120,14 +120,14 @@ jobs:
             **/**.go
             go.mod
             go.sum
-      - uses: actions/cache@v2.1.5
+      - uses: actions/cache@v2.1.6
         with:
           path: ~/go/pkg/mod
           key: ${{ runner.os }}-go-${{ hashFiles('**/go.sum') }}
           restore-keys: |
             ${{ runner.os }}-go-
         if: env.GIT_DIFF
-      - uses: actions/cache@v2.1.5
+      - uses: actions/cache@v2.1.6
         with:
           path: ~/go/bin
           key: ${{ runner.os }}-${{ github.sha }}-tm-binary