Show that we provide psr/simple-cache-implementation

Author: Nyholm

composer.json

@@ -36,7 +36,8 @@
         "cache/integration-tests": "^0.16"
     },
     "provide": {
-        "psr/cache-implementation": "^1.0"
+        "psr/cache-implementation": "^1.0",
+        "psr/simple-cache-implementation": "^1.0"
     },
     "autoload": {
         "psr-4": {