debian build environment is not a git repo
Without this patch, .rb files are not included in the deb

--- a/sentry-ruby-core.gemspec
+++ b/sentry-ruby-core.gemspec
@@ -12,7 +12,7 @@
   spec.platform = Gem::Platform::RUBY
   spec.required_ruby_version = '>= 2.4'
   spec.extra_rdoc_files = ["README.md", "LICENSE.txt"]
-  spec.files = `git ls-files | grep -Ev '^(spec|benchmarks|examples)'`.split("\n")
+  spec.files = Dir.glob("lib/**/*")
 
   spec.metadata["homepage_uri"] = spec.homepage
   spec.metadata["source_code_uri"] = spec.homepage