[branch-54] chore: update deps for cargo audit

Update crossbeam-epoch, postgres-protocol, quinn-proto, and
tokio-postgres to resolve RUSTSEC advisories, and ignore the two
quick-xml advisories that require an object_store 0.14 (breaking)
upgrade to fix.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: alamb

.github/workflows/audit.yml

@@ -51,4 +51,8 @@ jobs:
       - name: Run audit check
         # Note: you can ignore specific RUSTSEC issues using the `--ignore` flag ,for example:
         # run: cargo audit --ignore RUSTSEC-2026-0001
-        run: cargo audit
+        #
+        # RUSTSEC-2026-0194 and RUSTSEC-2026-0195 (quick-xml) are ignored because
+        # the fix requires quick-xml 0.41, which is only used by object_store 0.14,
+        # a breaking upgrade that can not be backported to this maintenance branch.
+        run: cargo audit --ignore RUSTSEC-2026-0194 --ignore RUSTSEC-2026-0195