fix: Ensure HTTP version negotiation for non-TLS requests

[0x676e67]

This pull request includes changes to improve HTTP version handling and testing in the rquest library. The most important changes include modifying the request version handling, adding new tests for HTTP versions, and removing outdated tests.

Improvements to HTTP version handling:

• examples/request_with_version.rs: Replaced println!("{:?}", resp.version()); with assert_eq!(resp.version(), Version::HTTP_11); to ensure the response version is HTTP/1.1.
• src/util/client/mod.rs: Added is_h2 method to check if the ALPN protocol is HTTP/2, and updated the request method to handle ALPN protocols correctly. [1] [2] [3] [4]

Testing improvements:

• tests/client.rs: Added new tests default_http_version, http1_version, and http2_version to validate the handling of different HTTP versions.
• tests/client.rs: Removed the outdated http2_upgrade test that required TLS support in the test server.

Code cleanup:

• tests/client.rs: Updated imports to include Version from the http crate.

close: #392