Fix Update Dependencies failing when two jobs push to main at once

.github/scripts/push-with-retry.sh

@@ -0,0 +1,35 @@
+#!/usr/bin/env bash
+#
+# Push the current branch, recovering from a push that lost a race.
+#
+# The dependency update jobs commit straight to main from several jobs at once,
+# so a rejected push is an expected outcome rather than a failure: another job
+# simply moved the branch first. Rebase the local commits onto the new remote
+# head and try again.
+
+set -euo pipefail
+
+attempts=${PUSH_RETRY_ATTEMPTS:-5}
+
+for ((attempt = 1; attempt <= attempts; attempt++)); do
+    if git push; then
+        echo "Pushed on attempt ${attempt} of ${attempts}"
+        exit 0
+    fi
+
+    if [ "${attempt}" -eq "${attempts}" ]; then
+        break
+    fi
+
+    echo "Push attempt ${attempt} of ${attempts} was rejected - another job moved the branch. Rebasing onto the latest remote head and retrying..."
+    sleep "$((attempt * 5))"
+
+    if ! git pull --rebase; then
+        git rebase --abort || true
+        echo "::error::Could not rebase onto the latest remote head"
+        exit 1
+    fi
+done
+
+echo "::error::Failed to push after ${attempts} attempts"
+exit 1