chore(deps): bump rexml from 3.2.8 to 3.3.6 in /frontend/android (#295)

Bumps [rexml](https://github.com/ruby/rexml) from 3.2.8 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@v3.2.8...v3.3.6)

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

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

frontend/android/Gemfile.lock

@@ -171,8 +171,8 @@ GEM
  trailblazer-option (>= 0.1.1, < 0.2.0)
  uber (< 0.2.0)
  retriable (3.1.2)
- rexml (3.2.8)
- strscan (>= 3.0.9)
+ rexml (3.3.6)
+ strscan
  rouge (2.0.7)
  ruby2_keywords (0.0.5)
  rubyzip (2.3.2)
@@ -197,13 +197,13 @@ GEM
  uber (0.1.0)
  unicode-display_width (2.5.0)
  word_wrap (1.0.0)
- xcodeproj (1.24.0)
+ xcodeproj (1.25.0)
  CFPropertyList (>= 2.3.3, < 4.0)
  atomos (~> 0.1.3)
  claide (>= 1.0.2, < 2.0)
  colored2 (~> 3.1)
  nanaimo (~> 0.3.0)
- rexml (~> 3.2.4)
+ rexml (>= 3.3.2, < 4.0)
  xcpretty (0.3.0)
  rouge (~> 2.0.7)
  xcpretty-travis-formatter (1.0.1)