Bump actions/cache from 2.1.5 to 2.1.6 (#36)

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@1a9e213...c64c572)

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

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

Author: dependabot[bot]

.github/workflows/ci.yml

@@ -36,7 +36,7 @@ jobs:
         pubspec-file-path: code/pubspec.yaml
     - name: Cache Flutter
       id: flutter-cache
-      uses: actions/cache@1a9e2138d905efd099035b49d8b7a3888c653ca8
+      uses: actions/cache@c64c572235d810460d0d6876e9c705ad5002b353
       with:
         path: flutter
         key: ${{ env.cache-name }}-ubuntu-latest-${{ steps.get-flutter-version.outputs.version }}-${{ hashFiles('code/pubspec.lock') }}

.github/workflows/deployment.yml

@@ -45,7 +45,7 @@ jobs:
         pubspec-file-path: code/pubspec.yaml
     - name: Cache Flutter
       id: flutter-cache
-      uses: actions/cache@1a9e2138d905efd099035b49d8b7a3888c653ca8
+      uses: actions/cache@c64c572235d810460d0d6876e9c705ad5002b353
       with:
         path: flutter
         key: ${{ env.cache-name }}-ubuntu-latest-${{ steps.get-flutter-version.outputs.version }}-${{ hashFiles('code/pubspec.lock') }}
@@ -123,7 +123,7 @@ jobs:
         pubspec-file-path: code/pubspec.yaml
     - name: Cache Flutter
       id: flutter-cache
-      uses: actions/cache@1a9e2138d905efd099035b49d8b7a3888c653ca8
+      uses: actions/cache@c64c572235d810460d0d6876e9c705ad5002b353
       with:
         path: flutter
         key: ${{ env.cache-name }}-${{ matrix.os }}-${{ steps.get-flutter-version.outputs.version }}-${{ hashFiles('code/pubspec.lock') }}