Show that we provide psr/simple-cache-implementation

Author: Nyholm

composer.json

@@ -38,7 +38,8 @@
         "ext-memcache": "The extension required to use this pool."
     },
     "provide": {
-        "psr/cache-implementation": "^1.0"
+        "psr/cache-implementation": "^1.0",
+        "psr/simple-cache-implementation": "^1.0"
     },
     "autoload": {
         "psr-4": {