Bump rexml from 3.2.5 to 3.3.3

Bumps [rexml](https://github.com/ruby/rexml) from 3.2.5 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@v3.2.5...v3.3.3)

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

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

Gemfile.lock

@@ -43,7 +43,8 @@ GEM
     multipart-post (2.1.1)
     public_suffix (4.0.6)
     rake (13.0.6)
-    rexml (3.2.5)
+    rexml (3.3.3)
+      strscan
     rspec (3.11.0)
       rspec-core (~> 3.11.0)
       rspec-expectations (~> 3.11.0)
@@ -58,6 +59,7 @@ GEM
       rspec-support (~> 3.11.0)
     rspec-support (3.11.0)
     ruby2_keywords (0.0.5)
+    strscan (3.1.0)
     webmock (3.14.0)
       addressable (>= 2.8.0)
       crack (>= 0.3.2)