Use HTTPS for RubyGems source to avoid MITM risk

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

Author: yahonda

Gemfile

@@ -1,4 +1,4 @@
-source "http://rubygems.org"
+source "https://rubygems.org"
 
 group :development do
   gem "juwelier", "~> 2.0"