Actualize used github action versions. Do not use specific version for cache action

Author: andrew-demb

.github/workflows/continuous_integration.yml

@@ -22,7 +22,7 @@ jobs:
     steps:
       # Cancel previous runs of the same branch
       - name: cancel
-        uses: styfle/cancel-workflow-action@0.9.1
+        uses: styfle/cancel-workflow-action@0.10.0
         with:
           access_token: ${{ github.token }}
 
@@ -41,7 +41,7 @@ jobs:
           echo "::set-output name=dir::$(composer config cache-files-dir)"
 
       - name: composer-cache
-        uses: actions/cache@v2.1.6
+        uses: actions/cache@v2
         with:
           path: ${{ steps.composercache.outputs.dir }}
           key: composer-${{ hashFiles('**/composer.json') }}-${{ matrix.install-args }}
@@ -59,7 +59,7 @@ jobs:
         run: vendor/bin/phpunit
 
       - name: phpstan-cache
-        uses: actions/cache@v2.1.6
+        uses: actions/cache@v2
         with:
           key: phpstan-${{ matrix.php-version }}-${{ matrix.install-args }}-${{ github.ref }}-${{ github.sha }}
           path: .phpstan-cache