Use version 1.0.0 of mailgun adapter

Author: drew-gross

package.json

@@ -37,7 +37,7 @@
     "parse-server-fs-adapter": "^1.0.0",
     "parse-server-gcs-adapter": "^1.0.0",
     "parse-server-s3-adapter": "^1.0.0",
-    "parse-server-simple-mailgun-adapter": "0.0.1",
+    "parse-server-simple-mailgun-adapter": "^1.0.0",
     "redis": "^2.5.0-1",
     "request": "^2.65.0",
     "tv4": "^1.2.7",