Update Ruby dependencies and ignore build artifacts

[hodovani]

This PR updates the Ruby dependencies by running bundle update to resolve pending Dependabot alerts for several gems, including activesupport, nokogiri, faraday, uri, rexml, and json. It also explicitly ignores build artifacts and local Bundler configurations (_site/, .bundle/, and vendor/bundle/) in the .gitignore file as requested.

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PR created automatically by Jules for task 15256189723474699506 started by @hodovani

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