Bump rexml from 3.2.6 to 3.2.8

Bumps [rexml](https://github.com/ruby/rexml) from 3.2.6 to 3.2.8.
- [Release notes](https://github.com/ruby/rexml/releases)
- [Changelog](https://github.com/ruby/rexml/blob/master/NEWS.md)
- [Commits](ruby/rexml@v3.2.6...v3.2.8)

---
updated-dependencies:
- dependency-name: rexml
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

Gemfile.lock

@@ -257,7 +257,8 @@ GEM
     rb-fsevent (0.11.2)
     rb-inotify (0.10.1)
       ffi (~> 1.0)
-    rexml (3.2.6)
+    rexml (3.2.8)
+      strscan (>= 3.0.9)
     rouge (3.26.0)
     ruby2_keywords (0.0.5)
     rubyzip (2.3.2)
@@ -272,6 +273,7 @@ GEM
       faraday (>= 0.17.3, < 3)
     simpleidn (0.2.1)
       unf (~> 0.1.4)
+    strscan (3.1.0)
     terminal-table (1.8.0)
       unicode-display_width (~> 1.1, >= 1.1.1)
     typhoeus (1.4.1)
@@ -284,7 +286,6 @@ GEM
     unf_ext (0.0.9.1-x64-mingw32)
     unicode-display_width (1.8.0)
     verbal_expressions (0.1.5)
-    wdm (0.1.1)
 
 PLATFORMS
   x64-mingw32
@@ -299,7 +300,6 @@ DEPENDENCIES
   jekyll-seo-tag
   jekyll-sitemap
   nokogiri (>= 1.15.4)
-  wdm (>= 0.1.1)
 
 BUNDLED WITH
    2.4.19