Enable auto-merge for bot-created PRs (#1490)

This still requires a human to review, but one less button to click.

.github/workflows/create-release.yml

diff --git a/.github/workflows/create-release.yml b/.github/workflows/create-release.yml
index 3f6aa00..0a55ec0 100644
--- a/.github/workflows/create-release.yml
+++ b/.github/workflows/create-release.yml
@@ -33,3 +33,7 @@
               https://chromium.googlesource.com/emscripten-releases/+/${{ inputs.lto-sha }} (LTO)
               https://chromium.googlesource.com/emscripten-releases/+/${{ inputs.nonlto-sha }} (asserts)
           delete-branch: true
+      - name: Enable auto-merge
+        run: gh pr merge --squash --auto "${{ steps.cpr.outputs.pull-request-number }}"
+        env:
+          GH_TOKEN: ${{ secrets.EMSCRIPTEN_BOT_TOKEN }}