Drop MPL licensed dependency dirs-sys

[pacak]

Dependabot updated dirs crate to version 5.0.0 here: https://github.com/openssh-rust/openssh/pull/114. Between versions 4.0 and 5.0 dirs crate included a small dependency with MPL license, there's several tickets to dirs crate about this issue closed as WONTFIX, you can find some relevant links here: https://github.com/harryfei/which-rs/pull/78

One possible solution is to pin dirs to some older version, but functionality used by openssh is simple enough to implement from scratch

[jonhoo]

This change is 

[NobodyXu]

Can you also update src/changelog.rs please?

[codecov-commenter]

Codecov Report

Attention: 2 lines in your changes are missing coverage. Please review.

Comparison is base (de229ce) 81.48% compared to head (26beda3) 81.33%.

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Additional details and impacted files

| [Files](https://app.codecov.io/gh/openssh-rust/openssh/pull/141?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None) | Coverage Δ | | |---|---|---| | [src/builder.rs](https://app.codecov.io/gh/openssh-rust/openssh/pull/141?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None#diff-c3JjL2J1aWxkZXIucnM=) | `76.25% <81.81%> (-0.32%)` | :arrow_down: | ... and [2 files with indirect coverage changes](https://app.codecov.io/gh/openssh-rust/openssh/pull/141/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None)

[NobodyXu]

Can you rebase against main please (not merge from main though)?

[NobodyXu]

I can do it for u from GH ui if you are ok with it

[pacak]

I can do it for u from GH ui if you are ok with it

Too late, I already did :)

[NobodyXu]

Will cut a release later today