MAINT: Rename main to v3-support (#2511) #2293

Job	Run time
py3.13 \| macos \| integration tests	5m 59s
mypy	4m 29s
py3.13 \| windows \| integration tests	5m 52s
py3.10 \| ubuntu \| integration tests	5m 54s
py3.10 \| ubuntu \| unit tests	5m 54s
py3.13 \| ubuntu \| integration tests	5m 53s
py3.11 \| ubuntu \| unit tests	5m 53s
py3.13 \| ubuntu \| unit tests	5m 55s
py3.13 \| macos \| unit tests	6m 1s
py3.13 \| windows \| unit tests	5m 51s
py3.12 \| ubuntu \| unit tests	5m 55s
merge-test-artifacts	1s
	1h 3m 37s

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