fix(postgres): remove home crate in favor of std::env::home_dir (#4171)

`home_dir()` was fixed in Rust 1.85 (rust-lang/rust#132515) and
un-deprecated in 1.87 (rust-lang/rust#137327). Since our MSRV is 1.86, the function is correct but still carries a deprecation warning until MSRV is bumped to 1.87.

This will allow other targets to compile including WebAssembly, see https://github.com/rust-lang/cargo/issues/12297