Bump rexml from 3.2.6 to 3.3.3

Bumps [rexml](https://github.com/ruby/rexml) from 3.2.6 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@v3.2.6...v3.3.3)

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

Signed-off-by: dependabot[bot] <[email protected]>

Gemfile.lock

@@ -196,7 +196,8 @@ GEM
       httparty (~> 0.14)
     regexp_parser (2.9.0)
     repost (0.4.2)
-    rexml (3.2.6)
+    rexml (3.3.3)
+      strscan
     rspec-core (3.13.0)
       rspec-support (~> 3.13.0)
     rspec-expectations (3.13.0)
@@ -235,6 +236,7 @@ GEM
       actionpack (>= 5.2)
       activesupport (>= 5.2)
       sprockets (>= 3.0.0)
+    strscan (3.1.0)
     thor (1.3.1)
     timeout (0.4.1)
     tzinfo (2.0.6)