Add Ruby workflow for embedded ruby code

[aramprice]

This PR adds a workflow to test the execution of the embedded ruby code against Rubies >= 2.6

The spec will not pass against Ruby > 3.4 because the ostruct gem required by the code is no longer part of the default gemset.

NOTE: the bosh-cli currently relies on whichever ruby executable is found in its $PATH when invoked, and does not have the capacity to install gems.

[Copilot]

Pull request overview

This PR adds a comprehensive Ruby testing infrastructure to validate embedded Ruby code execution across multiple Ruby versions (2.6 through head) and operating systems. The workflow addresses a known compatibility issue where Ruby versions > 3.4 no longer include the ostruct gem in the default gemset.

Key Changes:

• Added GitHub Actions workflow to test Ruby code against versions 2.6 through head
• Created RSpec test suite with specs for ERBRenderer initialization and rendering
• Modernized erb_renderer.rb with style improvements and safer Ruby patterns

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
.github/workflows/ruby.yml	Defines CI workflow to run specs across Ruby 2.6-head and ubuntu/macos
templatescompiler/erbrenderer/Gemfile	Adds test dependencies (rspec, standardrb, rake)
templatescompiler/erbrenderer/Rakefile	Configures rake tasks for running specs and linting
templatescompiler/erbrenderer/.gitignore	Excludes Gemfile.lock from version control
templatescompiler/erbrenderer/spec/spec_helper.rb	Sets up RSpec test environment and load paths
templatescompiler/erbrenderer/spec/erb_renderer_spec.rb	Adds test coverage for ERBRenderer initialization and template rendering
templatescompiler/erbrenderer/erb_renderer.rb	Applies style improvements, modernizes Ruby patterns (alias_method, File.write, JSON.load_file)

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[rkoster]

Running bundle install here masks a compatibility issue. The bundle install pulls in a newer json gem (≥2.5.0) which provides JSON.load_file, but this method doesn't exist in Ruby's stdlib json library for versions < 3.0.

[rkoster]

Suggested change

	context_hash = JSON.load_file(@json_context_path)
	context_hash = if JSON.respond_to?(:load_file)
	JSON.load_file(@json_context_path)
	else
	JSON.load(File.read(@json_context_path))
	end```