Bump rexml from 3.4.1 to 3.4.2 in /benchmarks/erubi-rails (#406)

Bumps [rexml](https://github.com/ruby/rexml) from 3.4.1 to 3.4.2.
- [Release notes](https://github.com/ruby/rexml/releases)
- [Changelog](https://github.com/ruby/rexml/blob/master/NEWS.md)
- [Commits](ruby/rexml@v3.4.1...v3.4.2)

---
updated-dependencies:
- dependency-name: rexml
  dependency-version: 3.4.2
  dependency-type: indirect
...

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

Author: dependabot[bot]

benchmarks/erubi-rails/Gemfile.lock

@@ -178,7 +178,7 @@ GEM
     regexp_parser (2.11.0)
     reline (0.6.2)
       io-console (~> 0.5)
-    rexml (3.4.1)
+    rexml (3.4.2)
     rubyzip (3.0.0)
     securerandom (0.4.1)
     selenium-webdriver (4.1.0)