Bump rexml from 3.2.6 to 3.3.0 in /apps/dashboard (#3620)

Bumps [rexml](https://github.com/ruby/rexml) from 3.2.6 to 3.3.0.
- [Release notes](https://github.com/ruby/rexml/releases)
- [Changelog](https://github.com/ruby/rexml/blob/master/NEWS.md)
- [Commits](ruby/rexml@v3.2.6...v3.3.0)

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

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

apps/dashboard/Gemfile.lock

@@ -234,7 +234,8 @@ GEM
       http-cookie (>= 1.0.2, < 2.0)
       mime-types (>= 1.16, < 4.0)
       netrc (~> 0.8)
-    rexml (3.2.6)
+    rexml (3.3.0)
+      strscan
     rss (0.3.0)
       rexml
     ruby2_keywords (0.0.5)
@@ -265,6 +266,7 @@ GEM
       activesupport (>= 5.2)
       sprockets (>= 3.0.0)
     stringio (3.1.0)
+    strscan (3.1.0)
     thor (1.3.1)
     tilt (2.3.0)
     timecop (0.9.8)