Bump rexml from 3.2.3 to 3.2.4 (#645)

Bumps [rexml](https://github.com/ruby/rexml) from 3.2.3 to 3.2.4.
- [Release notes](https://github.com/ruby/rexml/releases)
- [Changelog](https://github.com/ruby/rexml/blob/master/NEWS.md)
- [Commits](ruby/rexml@v3.2.3...v3.2.4)

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

Gemfile.lock

@@ -47,7 +47,7 @@ GEM
     rake (13.0.1)
     rake-compiler (1.1.0)
       rake
-    rexml (3.2.3)
+    rexml (3.2.4)
     rubocop (0.80.1)
       jaro_winkler (~> 1.5.1)
       parallel (~> 1.10)