Update semantic versioning on the ruby_http_client and minitest dependencies #111

Issue Summary

Here are the warnings from gem build

WARNING: pessimistic dependency on ruby_http_client (> 3.0.0) may be overly strict
if ruby_http_client is semantically versioned, use:
add_runtime_dependency 'ruby_http_client', '> 3.0', '>= 3.0.0'
WARNING: open-ended dependency on minitest (>= 0, development) is not recommended
if minitest is semantically versioned, use:
add_development_dependency 'minitest', '~> 0'