ci: Tests on PHP 7.4 only.

Author: drupol

.github/workflows/continuous-integration.yml

@@ -14,7 +14,7 @@ jobs:
             fail-fast: false
             matrix:
                 operating-system: [ubuntu-latest, windows-latest, macOS-latest]
-                php-versions: ['7.1', '7.2', '7.3', '7.4']
+                php-versions: ['7.4']
 
         steps:
             - name: Set git to use LF