build(deps): bump rexml from 3.3.4 to 3.3.6 in the bundler group

Bumps the bundler group with 1 update: [rexml](https://github.com/ruby/rexml).


Updates `rexml` from 3.3.4 to 3.3.6
- [Release notes](https://github.com/ruby/rexml/releases)
- [Changelog](https://github.com/ruby/rexml/blob/master/NEWS.md)
- [Commits](ruby/rexml@v3.3.4...v3.3.6)

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

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

Gemfile.lock

@@ -64,7 +64,7 @@ GEM
     rainbow (3.1.1)
     rake (13.2.1)
     regexp_parser (2.9.2)
-    rexml (3.3.4)
+    rexml (3.3.6)
       strscan
     rspec (3.13.0)
       rspec-core (~> 3.13.0)