Bump rexml from 3.2.5 to 3.3.9 in /postgres

Bumps [rexml](https://github.com/ruby/rexml) from 3.2.5 to 3.3.9.
- [Release notes](https://github.com/ruby/rexml/releases)
- [Changelog](https://github.com/ruby/rexml/blob/master/NEWS.md)
- [Commits](ruby/rexml@v3.2.5...v3.3.9)

---
updated-dependencies:
- dependency-name: rexml
  dependency-type: indirect
...

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

postgres/Gemfile.lock

@@ -32,7 +32,7 @@ GEM
     rainbow (3.1.1)
     rake (13.0.6)
     regexp_parser (2.8.0)
-    rexml (3.2.5)
+    rexml (3.3.9)
     rubocop (1.50.2)
       json (~> 2.3)
       parallel (~> 1.10)