refactor!: Replace `httpx` HTTP client with `impit` #351

Job	Run time
Type check / Type check (3.9)	14s
Type check / Type check (3.13)	14s
Lint check / Lint check (3.9)	12s
Type check / Type check (3.12)	15s
Type check / Type check (3.10)	14s
Lint check / Lint check (3.10)	7s
Lint check / Lint check (3.12)	8s
Lint check / Lint check (3.11)	9s
Type check / Type check (3.11)	14s
Lint check / Lint check (3.13)	12s
Unit tests / Unit tests (ubuntu-latest, 3.10)	22s
Async dostrings check / Async docstrings check	16s
Unit tests / Unit tests (ubuntu-latest, 3.12)	25s
Unit tests / Unit tests (ubuntu-latest, 3.9)	24s
Unit tests / Unit tests (windows-latest, 3.9)	40s
Unit tests / Unit tests (windows-latest, 3.11)	37s
Unit tests / Unit tests (windows-latest, 3.10)	35s
Unit tests / Unit tests (ubuntu-latest, 3.13)	26s
Unit tests / Unit tests (windows-latest, 3.13)	37s
Unit tests / Unit tests (ubuntu-latest, 3.11)	25s
Unit tests / Unit tests (windows-latest, 3.12)	37s
Docs check / Docs check	1m 2s
Integration tests / Approve integration tests for PRs from forks	2s
Integration tests / Integration tests	0s
Integration tests / Integration tests for PRs from forks	0s
	8m 27s

Provide feedback