chore(deps): bump pomerium/backport

Bumps [pomerium/backport](https://github.com/pomerium/backport) from a2e620de9fc4166f774ee2a389e170046cfad426 to 1.1.1. This release includes the previously tagged commit.
- [Release notes](https://github.com/pomerium/backport/releases)
- [Commits](pomerium/backport@a2e620d...e2ffd4c)

---
updated-dependencies:
- dependency-name: pomerium/backport
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

.github/workflows/backport.yaml

@@ -20,7 +20,7 @@ jobs:
           private_key: ${{ secrets.BACKPORT_APP_PRIVATE_KEY }}
 
       - name: Backport
-        uses: pomerium/backport@a2e620de9fc4166f774ee2a389e170046cfad426 # pin@retain_labels branch pending https://github.com/tibdex/backport/pull/79
+        uses: pomerium/backport@e2ffd4c5a70730dfd19046859dfaf366e3de6466 # pin@retain_labels branch pending https://github.com/tibdex/backport/pull/79
         with:
           github_token: ${{ steps.generate_token.outputs.token }}
           title_template: "{{originalTitle}}"