Add inputs/outputs to upgrade action (#241)

Per a user request, adds the following:
- Input for assignees
- Input to override the default created branch name
- Output the PR number and other PR info for consumption from other
actions

Verified
[run](https://github.com/trunk-io/trunk-action/actions/runs/9038985803/job/24841100064)

.github/workflows/weekly.yaml

@@ -26,6 +26,7 @@ jobs:
           private_key: ${{ secrets.TRUNK_OPEN_PR_APP_PRIVATE_KEY }}
 
       - name: Trunk Upgrade
+        id: upgrade
         uses: ./upgrade # external users: use trunk-io/trunk-action/upgrade@v1
         with:
           github-token: ${{ steps.generate-token.outputs.token }}

upgrade/action.yaml

@@ -43,6 +43,15 @@ inputs:
     required: false
     default: "false"
 
+  branch-name:
+    description: The branch name to generate the PR from
+    default: trunk-io/update-trunk
+    required: false
+
+  assignees:
+    description: A comma or newline separated list of GitHub assignee usernames
+    required: false
+
   reviewers:
     description: A comma or newline separated list of GitHub reviewer usernames
     required: false
@@ -61,6 +70,23 @@ inputs:
     description: A boolean to add a Signed-off-by line to the commit message
     required: false
     default: false
+outputs:
+  pull-request-number:
+    description: The pull request number
+    value: ${{ steps.cpr.outputs.pull-request-number }}
+
+  pull-request-url:
+    description: The URL of the pull request.
+    value: ${{ steps.cpr.outputs.pull-request-url }}
+
+  pull-request-operation:
+    description:
+      The pull request operation performed by the action, `created`, `updated` or `closed`.
+    value: ${{ steps.cpr.outputs.pull-request-operation }}
+
+  pull-request-head-sha:
+    description: The commit SHA of the pull request branch.
+    value: ${{ steps.cpr.outputs.pull-request-head-sha }}
 
 runs:
   using: composite
@@ -115,16 +141,18 @@ runs:
         ${{ github.action_path }}/../cleanup.sh
 
     - name: Create Pull Request
+      id: cpr
       uses: peter-evans/create-pull-request@v6
       with:
         title: ${{ inputs.prefix }}${{ env.PR_TITLE }}
         body: ${{ env.PR_DESCRIPTION }}
         base: ${{ inputs.base }}
-        branch: trunk-io/update-trunk
+        branch: ${{ inputs.branch-name }}
         labels: trunk
         add-paths: ${{ inputs.add-paths }}
         commit-message: ${{ inputs.prefix }}${{ env.PR_TITLE }}
         delete-branch: true
+        assignees: ${{ inputs.assignees }}
         reviewers: ${{ inputs.reviewers }}
         token: ${{ inputs.github-token }}
         signoff: ${{ inputs.signoff }}