Update Gemfile.lock for version 6.0.0

The gemspec version was bumped to 6.0.0 but Gemfile.lock still
referenced 5.0.1, causing bundler deployment mode to fail in CI.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Signed-off-by: Zack Koppert <zkoppert@github.com>

Author: zkoppert

Gemfile.lock

@@ -9,7 +9,7 @@ GIT
 PATH
   remote: .
   specs:
-    github-markup (5.0.1)
+    github-markup (6.0.0)
 
 GEM
   remote: https://rubygems.org/