refactor!: Replace `httpx` HTTP client with `impit` #330

Job	Run time
Type check / Type check (3.9)	13s
Type check / Type check (3.10)	14s
Type check / Type check (3.11)	17s
Type check / Type check (3.13)	15s
Type check / Type check (3.12)	17s
Lint check / Lint check (3.9)	8s
Lint check / Lint check (3.11)	11s
Async dostrings check / Async docstrings check	16s
Lint check / Lint check (3.10)	12s
Docs check / Docs check	59s
Lint check / Lint check (3.13)	12s
Unit tests / Unit tests (ubuntu-latest, 3.10)	12m 20s
Unit tests / Unit tests (windows-latest, 3.9)	12m 31s
Lint check / Lint check (3.12)	9s
Unit tests / Unit tests (ubuntu-latest, 3.12)	12m 20s
Unit tests / Unit tests (windows-latest, 3.11)	6m 50s
Unit tests / Unit tests (ubuntu-latest, 3.9)	6m 34s
Unit tests / Unit tests (ubuntu-latest, 3.13)	12m 19s
Unit tests / Unit tests (ubuntu-latest, 3.11)	6m 23s
Unit tests / Unit tests (windows-latest, 3.13)	6m 45s
Unit tests / Unit tests (windows-latest, 3.10)	6m 47s
Unit tests / Unit tests (windows-latest, 3.12)	6m 47s
Integration tests	0s
	1h 32m 59s

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