add php 7.3

Author: samsonasik

.github/workflows/ci_build.yml

@@ -13,7 +13,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        php-versions: ['8.0']
+        php-versions: ['7.3', '8.0']
     steps:
       - name: Setup PHP Action
         uses: shivammathur/setup-php@v2