Set minimum-stability to stable (#2411)

Author: dereuromark

composer.json

@@ -82,7 +82,7 @@
     "bin": [
         "bin/phinx"
     ],
-    "minimum-stability": "dev",
+    "minimum-stability": "stable",
     "prefer-stable": true,
     "config": {
         "allow-plugins": {