Update combined PR workflow to allow variable title

Author: mbklein

Diff for: .github/workflows/combine-prs.yml

@@ -16,7 +16,11 @@ on:
       combineBranchName:
         description: 'Name of the branch to combine PRs into'
         required: true
-        default: 'combine-prs-branch'
+        default: 'combined-dependencies'
+      combinePullRequestTitle:
+        description: 'Title of the combined Pull Request'
+        required: true
+        default: 'Dependency Rollup'
       ignoreLabel:
         description: 'Exclude PRs with this label'
         required: true
@@ -145,7 +149,7 @@ jobs:
             await github.rest.pulls.create({
               owner: context.repo.owner,
               repo: context.repo.repo,
-              title: 'Combined PR',
+              title: '${{ github.event.inputs.combinePullRequestTitle }}',
               head: '${{ github.event.inputs.combineBranchName }}',
               base: baseBranch,
               body: body