want to lint `binary_heap` in `manual_retain` when API is stabilized

[kyoto7250]

Description

I created manual_retain, but binary_heap_retain method is nightly API now, so we do not lint.

When this API is stabilized, we should lint binary_heap_retain as well.
It will work if we rewrite the process a little and add some tests.

If you have any questions, please ask me.

ref:

• code
• tests
• tracking issue

Version

No response

Additional Labels

@rustbot label +C-enhancement +good-first-issue

[unvalley]

It seems that binary_heap_retain API is stabilized in the PR (but not shipped yet). I'm interested in working on this.

[unvalley]

@rustbot claim