Merge pull request #231 from emacs-jp/dependabot/bundler/rexml-3.3.6

Bump rexml from 3.3.3 to 3.3.6

Author: syohex

Gemfile.lock

@@ -235,7 +235,7 @@ GEM
     rb-fsevent (0.11.0)
     rb-inotify (0.10.1)
       ffi (~> 1.0)
-    rexml (3.3.3)
+    rexml (3.3.6)
       strscan
     rouge (3.26.0)
     ruby2_keywords (0.0.4)