fix(deps): update dependency probot to v12 [security]

Author: renovate[bot]

package.json

@@ -12,7 +12,7 @@
   "dependencies": {
     "ejs": "^2.5.7",
     "jsdom": "^11.3.0",
-    "probot": "^6.0.0",
+    "probot": "^12.3.3",
     "probot-attachments": "github:probot/attachments",
     "unfurl.js": "^1.1.6"
   },