fix badly-formatted .all-contributorsrc file

Author: widdowquinn

.all-contributorsrc

@@ -215,12 +215,12 @@
       "contributions": [
         "bug"
       ]
-    },
+    }
   ],
   "contributorsPerLine": 7,
   "projectName": "pyani",
   "projectOwner": "widdowquinn",
   "repoType": "github",
   "repoHost": "https://github.com",
   "skipCi": true
-}
+}