feat: Faster JSON dumps in `format_message` with `msgspec` #4205

Job	Run time
External Tests	0s
Test on 3.7 (tests) / ubuntu-latest / SQLAlchemy: 2.*	23s
Test on 3.8 (tests) / ubuntu-latest / SQLAlchemy: 2.*	32s
Test on 3.9 (tests) / ubuntu-latest / SQLAlchemy: 2.*	27s
Test on 3.10 (tests) / ubuntu-latest / SQLAlchemy: 2.*	28s
Test on 3.11 (tests) / ubuntu-latest / SQLAlchemy: 2.*	33s
Test on 3.7 (tests) / macos-latest / SQLAlchemy: 2.*	1m 2s
Test on 3.8 (tests) / macos-latest / SQLAlchemy: 2.*	47s
Test on 3.9 (tests) / macos-latest / SQLAlchemy: 2.*	54s
Test on 3.10 (tests) / macos-latest / SQLAlchemy: 2.*	51s
Test on 3.11 (tests) / macos-latest / SQLAlchemy: 2.*	48s
Test on 3.7 (tests) / windows-latest / SQLAlchemy: 2.*	1m 58s
Test on 3.8 (tests) / windows-latest / SQLAlchemy: 2.*	1m 30s
Test on 3.9 (tests) / windows-latest / SQLAlchemy: 2.*	1m 42s
Test on 3.10 (tests) / windows-latest / SQLAlchemy: 2.*	1m 35s
Test on 3.11 (tests) / windows-latest / SQLAlchemy: 2.*	2m 5s
Test on 3.11 (tests) / ubuntu-latest / SQLAlchemy: 1.*	25s
Test on 3.10 (doctest) / ubuntu-latest / SQLAlchemy: 2.*	36s
Test on 3.8 (mypy) / ubuntu-latest / SQLAlchemy: 2.*	28s
Coverage	0s
	17m 4s

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