Build against JupyterLab 4.1, fix tests #1704

Job	Run time
jstest/lint (ubuntu, >=20,<21, >=4.1.0,<5.0.0a0, >=4)	4m 55s
build (ubuntu, >=20,<21, >=4.1.0,<5.0.0a0, >=4)	3m 4s
smoke source install ubuntu py3.8 lab>=4.1.0,<5	2m 26s
atest ubuntu py3.8 r>=4	8m 42s
smoke source install ubuntu py3.11 lab>=4.1.0,<5	2m 1s
atest ubuntu py3.11 r>=4	8m 41s
atest macos py3.8 r>=4	8m 45s
atest macos py3.11 r>=4	8m 44s
atest windows py3.8 r>=4	8m 29s
atest windows py3.11 r>=4	8m 33s
smoke ${{ matrix.os }} py${{ matrix.python }}	0s
	1h 4m 20s

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