Bump rexml from 3.3.3 to 3.3.6 (#1473)

Bumps [rexml](https://github.com/ruby/rexml) from 3.3.3 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@v3.3.3...v3.3.6)

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

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Gemfile.lock

@@ -375,7 +375,7 @@ GEM
  regexp_parser (2.9.2)
  reline (0.5.9)
  io-console (~> 0.5)
- rexml (3.3.3)
+ rexml (3.3.6)
  strscan
  rspec-core (3.13.0)
  rspec-support (~> 3.13.0)