chore(deps): update dependency json to v2 [security]

Signed-off-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

git-contributors.gemspec

@@ -26,5 +26,5 @@ Gem::Specification.new do |spec|
   spec.add_dependency 'git-issues', '~> 0'
   spec.add_dependency 'rest-client', '~> 1'
   spec.add_dependency 'zlog', '~> 0'
-  spec.add_dependency 'json', '~> 1.8'
+  spec.add_dependency 'json', '~> 2.3'
 end