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] <[email protected]>

Author: dependabot[bot]

Diff for: Gemfile.lock

@@ -67,8 +67,8 @@ GEM
       ffi (~> 1.0)
     rdoc (6.4.1.1)
       psych (>= 4.0.0)
-    rexml (3.2.8)
-      strscan (>= 3.0.9)
+    rexml (3.3.3)
+      strscan
     rouge (3.30.0)
     safe_yaml (1.0.5)
     sass (3.7.4)