[ruby/rubygems] Normalize host comparison in attestation_supported_host?

The method compared against a hardcoded string, so a trailing slash
(e.g. "https://rubygems.org/") would cause auto-attestation to be
silently skipped. Now we chomp the trailing slash and compare against
Gem::DEFAULT_HOST to be consistent with the rest of the codebase.

ruby/rubygems@a4fa24c8cf

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: 2 people

lib/rubygems/commands/push_command.rb

@@ -179,6 +179,7 @@ def get_push_scope
   end
 
   def attestation_supported_host?
-    (@host || Gem.host) == "https://rubygems.org"
+    host = (@host || Gem.host).to_s.chomp("/")
+    host == Gem::DEFAULT_HOST
   end
 end