Bump rexml from 3.2.6 to 3.3.9 in /pricing_catalog_rails_app

Bumps [rexml](https://github.com/ruby/rexml) from 3.2.6 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@v3.2.6...v3.3.9)

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

Signed-off-by: dependabot[bot] <[email protected]>

pricing_catalog_rails_app/Gemfile.lock

@@ -251,7 +251,7 @@ GEM
     regexp_parser (2.9.0)
     reline (0.4.2)
       io-console (~> 0.5)
-    rexml (3.2.6)
+    rexml (3.3.9)
     ruby2_keywords (0.0.5)
     ruby_event_store (2.15.0)
       concurrent-ruby (~> 1.0, >= 1.1.6)