Update version.json

***NO_CI***

version.json

@@ -10,6 +10,7 @@
   },
   "publicReleaseRefSpec": [
     "^refs/heads/master$",
+    "^refs/heads/main$",
     "^refs/heads/v\\d+(?:\\.\\d+)?$"
   ],
   "cloudBuild": {
@@ -21,4 +22,4 @@
     "versionIncrement": "build",
     "firstUnstableTag": "preview"
   }
-}
+}