[MSGPACK IDL] Gate feature by setting ENV #13940

Job	Run time
detect-python-versions	1s
lint	1m 6s
test-hypothesis (ubuntu-latest, 3.9)	5m 20s
build (ubuntu-latest, 3.9)	2m 35s
build-with-extras (ubuntu-latest, 3.9)	1m 25s
build-with-pandas (ubuntu-latest, 3.9, pandas<2.0.0, numpy<2.0.0)	2m 44s
test-hypothesis (ubuntu-latest, 3.12)	34s
build (ubuntu-latest, 3.12)	2m 48s
build-with-extras (ubuntu-latest, 3.12)	37s
build (windows-latest, 3.9)	5m 12s
build-with-pandas (ubuntu-latest, 3.9, pandas>=2.0.0, numpy>=2.0.0)	2m 55s
build-with-extras (windows-latest, 3.9)	4m 26s
build (windows-latest, 3.12)	5m 12s
build-with-pandas (ubuntu-latest, 3.12, pandas<2.0.0, numpy<2.0.0)	5m 20s
build-with-extras (windows-latest, 3.12)	4m 25s
integration (ubuntu-latest, 3.9, integration_test_codecov)	3m 46s
build-with-pandas (ubuntu-latest, 3.12, pandas>=2.0.0, numpy>=2.0.0)	3m 2s
build (macos-latest, 3.9)	1m 54s
build-with-extras (macos-latest, 3.9)	1m 27s
integration (ubuntu-latest, 3.9, integration_test_lftransfers_codecov)	3m 44s
build (macos-latest, 3.12)	1m 53s
build-with-extras (macos-latest, 3.12)	55s
integration (ubuntu-latest, 3.12, integration_test_codecov)	4m 21s
integration (ubuntu-latest, 3.12, integration_test_lftransfers_codecov)	4m 25s
test-serialization (ubuntu-latest, 3.9)	3m 22s
test-serialization (ubuntu-latest, 3.12)	3m 21s
build-plugins	1s
	1h 16m 51s

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