Add php 8 to php-versions on ci

Author: juanmiguelbesada

.github/workflows/ci.yml

@@ -8,7 +8,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, windows-latest, macOS-latest]
-        php-versions: ['7.4']
+        php-versions: ['7.4', '8.0']
 
     name: Test on ${{ matrix.os }} with PHP ${{ matrix.php-versions }}
     steps: