Drop debase, it doesn't yet support Ruby 3.1

This dependency was added in dependabot#5086.

However, `debase` doesn't currently support Ruby 3 or 3.1: ruby-debug/ruby-debug-ide#223 (comment)

Ruby 3.1 now bundles the `debug` gem. This new `debug` gem has
functionality that replaces `debase` + the `ruby-debug-ide` gem so I
removed those as well.

Even though the `debug` gem is bundled, we still need to pin it in the
`gemspec` file because we use a customized `GEM_PATH`. The `debug` gem
bundled with Ruby by default is no longer found since it lives in the
default `GEM_PATH`.

common/dependabot-common.gemspec

@@ -35,15 +35,12 @@ Gem::Specification.new do |spec|
   spec.add_dependency "parser", ">= 2.5", "< 4.0"
   spec.add_dependency "toml-rb", ">= 1.1.2", "< 3.0"
 
-  spec.add_development_dependency "debase", "0.2.3"
-  spec.add_development_dependency "debase-ruby_core_source", "0.10.16"
   spec.add_development_dependency "debug", ">= 1.0.0"
   spec.add_development_dependency "gpgme", "~> 2.0"
   spec.add_development_dependency "rake", "~> 13"
   spec.add_development_dependency "rspec", "~> 3.8"
   spec.add_development_dependency "rspec-its", "~> 1.2"
   spec.add_development_dependency "rubocop", "~> 1.31.2"
-  spec.add_development_dependency "ruby-debug-ide", "~> 0.7.3"
   spec.add_development_dependency "simplecov", "~> 0.21.0"
   spec.add_development_dependency "simplecov-console", "~> 0.9.1"
   spec.add_development_dependency "stackprof", "~> 0.2.16"