Compliance with Rack : Spec 3. Lower-case HTTP Headers

[KarenSido]

Hi, I was wondering if rack-mini-profiler intends to be compliant with Rack linter (spec 3), and to HTTP 2 standards, which asks to make HTTP Headers lower-case (although they are "compared in a case-insensitive fashion".. don't ask me why).

Error 500:

Rack::Lint::LintError: uppercase character in header name: Content-Type (Rack::Lint::LintError)
	/home/karen/.rbenv/versions/3.2.2/lib/ruby/gems/3.2.0/gems/rack-3.0.9/lib/rack/lint.rb:653:in `block in check_headers'
	/home/karen/.rbenv/versions/3.2.2/lib/ruby/gems/3.2.0/gems/rack-3.0.9/lib/rack/lint.rb:637:in `each'
	/home/karen/.rbenv/versions/3.2.2/lib/ruby/gems/3.2.0/gems/rack-3.0.9/lib/rack/lint.rb:637:in `check_headers'
	/home/karen/code/lcas/config/initializers/rack_lint_websocket.rb:38:in `check_headers'
	/home/karen/.rbenv/versions/3.2.2/lib/ruby/gems/3.2.0/gems/rack-3.0.9/lib/rack/lint.rb:73:in `response'
	/home/karen/.rbenv/versions/3.2.2/lib/ruby/gems/3.2.0/gems/rack-3.0.9/lib/rack/lint.rb:35:in `call'
	/home/karen/code/lcas/config/initializers/rack_lint_websocket.rb:9:in `call'
	/home/karen/.rbenv/versions/3.2.2/lib/ruby/gems/3.2.0/gems/rack-3.0.9/lib/rack/show_exceptions.rb:27:in `call'
	/home/karen/.rbenv/versions/3.2.2/lib/ruby/gems/3.2.0/gems/rack-3.0.9/lib/rack/common_logger.rb:43:in `call'
	/home/karen/.rbenv/versions/3.2.2/lib/ruby/gems/3.2.0/gems/rack-3.0.9/lib/rack/content_length.rb:20:in `call'
	/home/karen/.rbenv/versions/3.2.2/lib/ruby/gems/3.2.0/gems/puma-6.4.2/lib/puma/configuration.rb:272:in `call'
	/home/karen/.rbenv/versions/3.2.2/lib/ruby/gems/3.2.0/gems/puma-6.4.2/lib/puma/request.rb:100:in `block in handle_request'
	/home/karen/.rbenv/versions/3.2.2/lib/ruby/gems/3.2.0/gems/puma-6.4.2/lib/puma/thread_pool.rb:378:in `with_force_shutdown'
	/home/karen/.rbenv/versions/3.2.2/lib/ruby/gems/3.2.0/gems/puma-6.4.2/lib/puma/request.rb:99:in `handle_request'
	/home/karen/.rbenv/versions/3.2.2/lib/ruby/gems/3.2.0/gems/puma-6.4.2/lib/puma/server.rb:464:in `process_client'
	/home/karen/.rbenv/versions/3.2.2/lib/ruby/gems/3.2.0/gems/puma-6.4.2/lib/puma/server.rb:245:in `block in run'
	/home/karen/.rbenv/versions/3.2.2/lib/ruby/gems/3.2.0/gems/puma-6.4.2/lib/puma/thread_pool.rb:155:in `block in spawn_thread'
127.0.0.1 - - [12/Feb/2024:09:17:00 +0100] "POST /mini-profiler-resources/results HTTP/1.1" 500 1958 0.012

Am I missing something about rack settings that could disable this rule ? Anyway, it would be nice to make rack mini profiler compliant.
Actually, in order to make rack-mini-profiler to work, I have to patch Rack method check_headers and use Rack Headers class to format rack mini profiler headers (and so all headers from my app, although they are compliant) to avoid this error.

class ::Rack::Lint::Wrapper
    alias check_headers_orig check_headers
    def check_headers(headers)
        headers = Rack::Headers.new(headers)
        
        check_headers_orig(headers)
    end
end

HTTP 2 Standards for lower-case headers:
https://www.rfc-editor.org/rfc/rfc7540#section-8.1.2

Origin issue for lower-case headers of Rack:
rack/rack#1592