Bump rexml from 3.4.1 to 3.4.4

Bumps [rexml](https://github.com/ruby/rexml) from 3.4.1 to 3.4.4.
- [Release notes](https://github.com/ruby/rexml/releases)
- [Changelog](https://github.com/ruby/rexml/blob/master/NEWS.md)
- [Commits](https://github.com/ruby/rexml/compare/v3.4.1...v3.4.4)

---
updated-dependencies:
- dependency-name: rexml
  dependency-version: 3.4.4
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Gemfile.lock

@@ -315,7 +315,7 @@ GEM
       io-console (~> 0.5)
     reverse_markdown (3.0.0)
       nokogiri
-    rexml (3.4.1)
+    rexml (3.4.4)
     rspec-expectations (3.13.5)
       diff-lcs (>= 1.2.0, < 2.0)
       rspec-support (~> 3.13.0)