Merge pull request #856 from Parallel-in-Time/dependabot/bundler/rexml-3.3.9

Bump rexml from 3.3.6 to 3.3.9

Author: pancetta

Gemfile.lock

@@ -100,8 +100,7 @@ GEM
     rb-fsevent (0.11.2)
     rb-inotify (0.10.1)
       ffi (~> 1.0)
-    rexml (3.3.6)
-      strscan
+    rexml (3.3.9)
     rouge (4.1.3)
     safe_yaml (1.0.5)
     sass (3.7.4)
@@ -113,7 +112,6 @@ GEM
     sass-listen (4.0.0)
       rb-fsevent (~> 0.9, >= 0.9.4)
       rb-inotify (~> 0.9, >= 0.9.7)
-    strscan (3.1.0)
     terminal-table (3.0.2)
       unicode-display_width (>= 1.1.1, < 3)
     trollop (2.9.9)