Merge pull request #56 from cakephp/php8-ci

Add PHP8 to CI.

Author: markstory

.github/workflows/ci.yaml

@@ -14,7 +14,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        php-version: ['7.2', '7.4']
+        php-version: ['7.2', '7.4', '8.0']
         prefer-lowest: ['']
         include:
           - php-version: '7.2'
@@ -49,7 +49,7 @@ jobs:
         if ${{ matrix.prefer-lowest == 'prefer-lowest' }}; then
           composer update --prefer-lowest --prefer-stable
         else
-          composer install
+          composer update
         fi
 
     - name: Run PHPUnit
@@ -61,7 +61,7 @@ jobs:
         fi
 
     - name: Code Coverage Report
-      if: success() && matrix.php-version == '7.4' && matrix.db-type == 'mysql'
+      if: success() && matrix.php-version == '7.4'
       uses: codecov/codecov-action@v1
 
   cs-stan: