Reverse mirroring order.

.github/workflows/mirror.yml

@@ -6,20 +6,20 @@
 on:
   push:
     branches:
-      - 'master'
+      - 'main'
 
 jobs:
   mirror_job:
     permissions:
       pull-requests: write
     runs-on: ubuntu-latest
     if: ${{ github.repository == 'flutter/gallery' }}
-    name: Mirror master branch to main branch
+    name: Mirror main branch to master branch
     steps:
       - name: Mirror action step
         id: mirror
         uses: google/mirror-branch-action@c6b07e441a7ffc5ae15860c1d0a8107a3a151db8
         with:
           github-token: ${{ secrets.FLUTTERMIRRORINGBOT_TOKEN }}
-          source: 'master'
-          dest: 'main'
+          source: 'main'
+          dest: 'master'