Bump rexml from 3.3.0 to 3.3.9

Bumps [rexml](https://github.com/ruby/rexml) from 3.3.0 to 3.3.9.
- [Release notes](https://github.com/ruby/rexml/releases)
- [Changelog](https://github.com/ruby/rexml/blob/master/NEWS.md)
- [Commits](ruby/rexml@v3.3.0...v3.3.9)

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

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

Author: dependabot[bot]

Gemfile.lock

@@ -24,6 +24,7 @@ GEM
       http_parser.rb (~> 0)
     ethon (0.16.0)
       ffi (>= 1.15.0)
+    eventmachine (1.2.7)
     eventmachine (1.2.7-x64-mingw32)
     execjs (2.9.1)
     faraday (2.8.1)
@@ -32,6 +33,7 @@ GEM
       ruby2_keywords (>= 0.0.4)
     faraday-net_http (3.0.2)
     ffi (1.17.0-x64-mingw32)
+    ffi (1.17.0-x86_64-linux-gnu)
     forwardable-extended (2.6.0)
     gemoji (3.0.1)
     github-pages (225)
@@ -208,11 +210,15 @@ GEM
       rb-fsevent (~> 0.10, >= 0.10.3)
       rb-inotify (~> 0.9, >= 0.9.10)
     mercenary (0.3.6)
+    mini_portile2 (2.8.7)
     minima (2.5.1)
       jekyll (>= 3.5, < 5.0)
       jekyll-feed (~> 0.9)
       jekyll-seo-tag (~> 2.1)
     minitest (5.24.0)
+    nokogiri (1.15.6)
+      mini_portile2 (~> 2.8.2)
+      racc (~> 1.4)
     nokogiri (1.15.6-x64-mingw32)
       racc (~> 1.4)
     octokit (4.25.1)
@@ -225,8 +231,7 @@ GEM
     rb-fsevent (0.11.2)
     rb-inotify (0.11.1)
       ffi (~> 1.0)
-    rexml (3.3.0)
-      strscan
+    rexml (3.3.9)
     rouge (3.26.0)
     ruby2_keywords (0.0.5)
     rubyzip (2.3.2)
@@ -240,7 +245,6 @@ GEM
       addressable (>= 2.3.5)
       faraday (>= 0.17.3, < 3)
     simpleidn (0.2.3)
-    strscan (3.1.0)
     terminal-table (1.8.0)
       unicode-display_width (~> 1.1, >= 1.1.1)
     thread_safe (0.3.6)
@@ -254,6 +258,7 @@ GEM
 
 PLATFORMS
   x64-mingw32
+  x86_64-linux
 
 DEPENDENCIES
   github-pages (~> 225)