* Preserve individual headers with the same name on responses
* Rename RequestHeadersDict to HTTPHeadersDict
* Update tests/utils/http_server.py
* Update tests/utils/http_server.py
* Update httpie/adapters.py
Co-authored-by: Jakub Roztocil <jakub@roztocil.co>
Some of the tests now use the `httpbin_both` fixture from pytest-httpbin.
Also, made httpbin's CA trusted by default and added `httpbin_secure_untrusted`
fixture to allow overriding that for particular tests.