Make release-plan work for v3

.github/workflows/plan-release.yml

@@ -2,15 +2,14 @@ name: Release Plan Review
 on:
   push:
     branches:
-      - main
-      - master
+      - v3.x
   pull_request_target: # This workflow has permissions on the repo, do NOT run code from PRs in this workflow. See https://securitylab.github.com/research/github-actions-preventing-pwn-requests/
     types:
       - labeled
       - unlabeled
 
 concurrency:
-  group: plan-release # only the latest one of these should ever be running
+  group: plan-release-v3 # only the latest one of these should ever be running
   cancel-in-progress: true
 
 jobs:
@@ -24,7 +23,7 @@ jobs:
       - uses: actions/checkout@v4
         with:
           fetch-depth: 0
-          ref: 'master'
+          ref: 'v3.x'
       # This will only cause the `check-plan` job to have a "command" of `release`
       # when the .release-plan.json file was changed on the last commit.
       - id: check-release
@@ -50,7 +49,7 @@ jobs:
         # github-changelog can discover what's changed since the last release
         with:
           fetch-depth: 0
-          ref: 'master'
+          ref: 'v3.x'
       - uses: actions/setup-node@v4
         with:
           node-version: 18
@@ -79,7 +78,7 @@ jobs:
         with:
           commit-message: "Prepare Release using 'release-plan'"
           labels: "internal"
-          branch: release-preview
+          branch: release-preview-v3
           title: Prepare Release
           body: |
             This PR is a preview of the release that [release-plan](https://github.com/embroider-build/release-plan) has prepared. To release you should just merge this PR 👍

.github/workflows/publish.yml

@@ -8,11 +8,10 @@ on:
   workflow_dispatch:
   push:
     branches:
-      - main
-      - master
+      - v3.x
 
 concurrency:
-  group: publish-${{ github.head_ref || github.ref }}
+  group: publish-v3-${{ github.head_ref || github.ref }}
   cancel-in-progress: true
 
 jobs:
@@ -26,7 +25,7 @@ jobs:
       - uses: actions/checkout@v4
         with:
           fetch-depth: 0
-          ref: 'master'
+          ref: 'v3.x'
       # This will only cause the `check-plan` job to have a result of `success`
       # when the .release-plan.json file was changed on the last commit. This
       # plus the fact that this action only runs on main will be enough of a guard
@@ -52,7 +51,7 @@ jobs:
       - uses: pnpm/action-setup@v4
       - run: pnpm install --frozen-lockfile
       - name: npm publish
-        run: pnpm release-plan publish
+        run: pnpm release-plan publish --publish-branch v3.x --tag legacy-v3
         env:
           GITHUB_AUTH: ${{ secrets.GITHUB_TOKEN }}
           NODE_AUTH_TOKEN: ${{ secrets.NPM_TOKEN }}