Update github_changelog_generator requirement from 1.15.2 to 1.16.1 (#38)

Updates the requirements on [github_changelog_generator](https://github.com/github-changelog-generator/Github-Changelog-Generator) to permit the latest version.
- [Release notes](https://github.com/github-changelog-generator/Github-Changelog-Generator/releases)
- [Changelog](https://github.com/github-changelog-generator/github-changelog-generator/blob/master/CHANGELOG.md)
- [Commits](github-changelog-generator/github-changelog-generator@v1.15.2...v1.16.1)

Signed-off-by: dependabot[bot] <[email protected]>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

Gemfile

@@ -1,3 +1,3 @@
 source 'https://rubygems.org' do
-  gem 'github_changelog_generator', '1.15.2'
+  gem 'github_changelog_generator', '1.16.1'
 end