Bump rexml from 3.2.8 to 3.3.3

Bumps [rexml](https://github.com/ruby/rexml) from 3.2.8 to 3.3.3.
- [Release notes](https://github.com/ruby/rexml/releases)
- [Changelog](https://github.com/ruby/rexml/blob/master/NEWS.md)
- [Commits](ruby/rexml@v3.2.8...v3.3.3)

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

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

Gemfile.lock

@@ -213,8 +213,8 @@ GEM
     regexp_parser (2.8.2)
     reline (0.5.6)
       io-console (~> 0.5)
-    rexml (3.2.8)
-      strscan (>= 3.0.9)
+    rexml (3.3.3)
+      strscan
     rspec (3.12.0)
       rspec-core (~> 3.12.0)
       rspec-expectations (~> 3.12.0)