Update dependency rexml to v3.2.7 [SECURITY]

Author: renovate[bot]

Gemfile.lock

@@ -432,7 +432,8 @@ GEM
       http-cookie (>= 1.0.2, < 2.0)
       mime-types (>= 1.16, < 4.0)
       netrc (~> 0.8)
-    rexml (3.2.5)
+    rexml (3.2.8)
+      strscan (>= 3.0.9)
     ruby2_keywords (0.0.5)
     rubyzip (2.3.2)
     sass-rails (6.0.0)
@@ -482,6 +483,7 @@ GEM
     spy (1.0.1)
     strong_migrations (1.4.0)
       activerecord (>= 5.2)
+    strscan (3.1.0)
     swd (1.3.0)
       activesupport (>= 3)
       attr_required (>= 0.0.5)