fix naming bump type (#4732)

Author: dmceachernmsft

.github/workflows/create-prerelease-branch.yml

@@ -141,8 +141,8 @@ jobs:
       - name: Hop into new branch
         id: groombranch
         run: |
-          git checkout -b groom-changelog-${{github.event.inputs.bumptype}}/${{ steps.version.outputs.version }}
-          echo "groombranch=groom-changelog-${{github.event.inputs.bumptype}}/${{ steps.version.outputs.version }}" >> $GITHUB_OUTPUT
+          git checkout -b groom-changelog-${{github.event.inputs.bump_type}}/${{ steps.version.outputs.version }}
+          echo "groombranch=groom-changelog-${{github.event.inputs.bump_type}}/${{ steps.version.outputs.version }}" >> $GITHUB_OUTPUT
 
       - name: Add trivial changefile so CI does not complain about the CHANGELOG grooming PR
         run: |