Bump rexml from 3.3.0 to 3.3.3 (#770)

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

Author: dependabot[bot]

Gemfile.lock

@@ -308,7 +308,7 @@ GEM
     responders (3.1.1)
       actionpack (>= 5.2)
       railties (>= 5.2)
-    rexml (3.3.0)
+    rexml (3.3.3)
       strscan
     rouge (4.1.2)
     rspec-core (3.12.2)