feat: APCu caching driver: extension suggestion

Author: sk757a

admin/framework/composer.json

@@ -27,6 +27,7 @@
         "predis/predis": "^3.0"
     },
     "suggest": {
+        "ext-apcu": "If you use Cache class ApcuHandler",
         "ext-curl": "If you use CURLRequest class",
         "ext-dom": "If you use TestResponse",
         "ext-exif": "If you run Image class tests",

composer.json

@@ -35,6 +35,7 @@
         "codeigniter4/framework": "self.version"
     },
     "suggest": {
+        "ext-apcu": "If you use Cache class ApcuHandler",
         "ext-curl": "If you use CURLRequest class",
         "ext-dom": "If you use TestResponse",
         "ext-exif": "If you run Image class tests",