Change minimum Python to 3.9 and add Trio sample (#162) #566

Job	Run time
build-lint-test (3.9, ubuntu-latest)	5m 3s
build-lint-test (3.9, macos-intel)	5m 32s
build-lint-test (3.9, macos-arm)	5m 16s
build-lint-test (3.9, windows-latest)	6m 10s
build-lint-test (3.12, ubuntu-latest)	5m 39s
build-lint-test (3.12, macos-intel)	6m 39s
build-lint-test (3.12, macos-arm)	5m 18s
build-lint-test (3.12, windows-latest)	6m 34s
	46m 11s

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