feat: Faster JSON dumps in `format_message` with `msgspec` #3825

Job	Run time
Test on 3.7 (tests) / ubuntu-latest / SQLAlchemy: 2.*	27s
Test on 3.8 (tests) / ubuntu-latest / SQLAlchemy: 2.*	1m 15s
Test on 3.9 (tests) / ubuntu-latest / SQLAlchemy: 2.*	1m 32s
Test on 3.10 (tests) / ubuntu-latest / SQLAlchemy: 2.*	1m 26s
Test on 3.11 (tests) / ubuntu-latest / SQLAlchemy: 2.*	1m 15s
Test on 3.7 (tests) / macos-latest / SQLAlchemy: 2.*	2m 42s
Test on 3.8 (tests) / macos-latest / SQLAlchemy: 2.*	2m 4s
Test on 3.9 (tests) / macos-latest / SQLAlchemy: 2.*	4m 43s
Test on 3.10 (tests) / macos-latest / SQLAlchemy: 2.*	4m 19s
Test on 3.11 (tests) / macos-latest / SQLAlchemy: 2.*	3m 1s
Test on 3.7 (tests) / windows-latest / SQLAlchemy: 2.*	1m 35s
Test on 3.8 (tests) / windows-latest / SQLAlchemy: 2.*	2m 45s
Test on 3.9 (tests) / windows-latest / SQLAlchemy: 2.*	3m 12s
Test on 3.10 (tests) / windows-latest / SQLAlchemy: 2.*	2m 58s
Test on 3.11 (tests) / windows-latest / SQLAlchemy: 2.*	2m 35s
Test on 3.11 (tests) / ubuntu-latest / SQLAlchemy: 1.*	1m 15s
Test on 3.10 (doctest) / ubuntu-latest / SQLAlchemy: 2.*	50s
Test on 3.8 (mypy) / ubuntu-latest / SQLAlchemy: 2.*	48s
External Tests	0s
Coverage	0s
	38m 42s

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