refactor: reduce dependency on futures-core / futures-util

[0x676e67]

This pull request focuses on replacing the futures_util::ready! macro with the std::task::ready! macro across multiple files to streamline the codebase. The changes span several modules, including body.rs, decoder.rs, websocket/mod.rs, dns.rs, http.rs, pool.rs, and oneshot.rs.

Macro Replacement:

• src/client/body.rs: Replaced futures_util::ready! with std::task::ready! in various functions and implementations. [1] [2] [3] [4] [5] [6]
• src/client/decoder.rs: Updated the macro usage in several impl HttpBody for Decoder blocks and other functions. [1] [2] [3] [4] [5] [6] [7] [8]
• src/client/websocket/mod.rs: Changed the macro in the impl Stream for WebSocket. [1] [2]
• src/util/client/connect/dns.rs: Replaced the macro in the resolve function. [1] [2]
• src/util/client/connect/http.rs: Updated the macro in the poll_ready function. [1] [2]
• src/util/client/pool.rs: Modified the macro usage in the file.
• src/util/service/oneshot.rs: Replaced the macro in the file.

[0x676e67]

ref: seanmonstar/reqwest#2557