Merge pull request #1246 from pkp/dependabot/bundler/rexml-3.3.6

Bump rexml from 3.3.3 to 3.3.6

Author: emmauhl

Gemfile.lock

@@ -60,7 +60,7 @@ GEM
     rb-fsevent (0.11.1)
     rb-inotify (0.10.1)
       ffi (~> 1.0)
-    rexml (3.3.3)
+    rexml (3.3.6)
       strscan
     rouge (3.28.0)
     safe_yaml (1.0.5)