github-actions(deps): update actions/cache requirement to v2.1.5

Updates the requirements on [actions/cache](https://github.com/actions/cache) to permit the latest version.
- [Release notes](https://github.com/actions/cache/releases)
- [Commits](https://github.com/actions/cache/commits/1a9e2138d905efd099035b49d8b7a3888c653ca8)

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

.github/workflows/continuous-integration.yml

@@ -92,7 +92,7 @@ jobs:
         run: "echo \"::set-output name=directory::$(composer config cache-dir)\""
 
       - name: "Cache dependencies installed with composer"
-        uses: "actions/cache@v2.1.4"
+        uses: "actions/cache@v2.1.5"
         with:
           path: "${{ steps.determine-composer-cache-directory.outputs.directory }}"
           key: "php-${{ matrix.php-version }}-composer-${{ matrix.dependencies }}-${{ hashFiles('composer.lock') }}"
@@ -144,7 +144,7 @@ jobs:
         run: "echo \"::set-output name=directory::$(composer config cache-dir)\""
 
       - name: "Cache dependencies installed with composer"
-        uses: "actions/cache@v2.1.4"
+        uses: "actions/cache@v2.1.5"
         with:
           path: "${{ steps.determine-composer-cache-directory.outputs.directory }}"
           key: "php-${{ matrix.php-version }}-composer-${{ matrix.dependencies }}-${{ hashFiles('composer.lock') }}"
@@ -196,7 +196,7 @@ jobs:
         run: "echo \"::set-output name=directory::$(composer config cache-dir)\""
 
       - name: "Cache dependencies installed with composer"
-        uses: "actions/cache@v2.1.3"
+        uses: "actions/cache@v2.1.5"
         with:
           path: "${{ steps.determine-composer-cache-directory.outputs.directory }}"
           key: "php-${{ matrix.php-version }}-composer-${{ matrix.dependencies }}-${{ hashFiles('composer.lock') }}"
@@ -249,7 +249,7 @@ jobs:
         run: "echo \"::set-output name=directory::$(composer config cache-dir)\""
 
       - name: "Cache dependencies installed with composer"
-        uses: "actions/cache@v2.1.4"
+        uses: "actions/cache@v2.1.5"
         with:
           path: "${{ steps.determine-composer-cache-directory.outputs.directory }}"
           key: "php-${{ matrix.php-version }}-composer-${{ matrix.dependencies }}-${{ hashFiles('composer.lock') }}"
@@ -317,7 +317,7 @@ jobs:
         run: "echo \"::set-output name=directory::$(composer config cache-dir)\""
 
       - name: "Cache dependencies installed with composer"
-        uses: "actions/cache@v2.1.4"
+        uses: "actions/cache@v2.1.5"
         with:
           path: "${{ steps.determine-composer-cache-directory.outputs.directory }}"
           key: "php-${{ matrix.php-version }}-composer-${{ matrix.dependencies }}-${{ hashFiles('composer.lock') }}"
@@ -373,7 +373,7 @@ jobs:
         run: "echo \"::set-output name=directory::$(composer config cache-dir)\""
 
       - name: "Cache dependencies installed with composer"
-        uses: "actions/cache@v2.1.4"
+        uses: "actions/cache@v2.1.5"
         with:
           path: "${{ steps.determine-composer-cache-directory.outputs.directory }}"
           key: "php-${{ matrix.php-version }}-composer-${{ matrix.dependencies }}-${{ hashFiles('composer.lock') }}"