Add funding URI to gemspec

Author: andrew

git-pkgs.gemspec

@@ -17,6 +17,7 @@ Gem::Specification.new do |spec|
   spec.metadata["homepage_uri"] = spec.homepage
   spec.metadata["source_code_uri"] = spec.homepage
   spec.metadata["changelog_uri"] = "#{spec.homepage}/blob/main/CHANGELOG.md"
+  spec.metadata["funding_uri"] = "https://github.com/sponsors/andrew"
 
   gemspec = File.basename(__FILE__)
   spec.files = IO.popen(%w[git ls-files -z], chdir: __dir__, err: IO::NULL) do |ls|