Merge pull request #2600 from prometheus/dependabot/bundler/rexml-3.3.9

Bump rexml from 3.2.5 to 3.3.9

Author: SuperQ

Gemfile.lock

@@ -111,7 +111,7 @@ GEM
     rb-inotify (0.10.1)
       ffi (~> 1.0)
     redcarpet (3.6.0)
-    rexml (3.2.5)
+    rexml (3.3.9)
     rspec (3.12.0)
       rspec-core (~> 3.12.0)
       rspec-expectations (~> 3.12.0)