Fixes for glTF exports #249

Job	Run time
initial_checks / Load tox environments	9s
initial_checks / codestyle (ubuntu-latest)	22s
deploy-examples	0s
tests / Load tox environments	3s
tests / py39-test-all (ubuntu-latest)	3m 54s
tests / py310-test-all (ubuntu-latest)	3m 28s
tests / py311-test-all (ubuntu-latest)	4m 41s
tests / py312-test-all (ubuntu-latest)	3m 53s
tests / py312-test-qt (ubuntu-latest)	4m 28s
tests / py312-test-jupyter (ubuntu-latest)	2m 58s
tests / py39-test-all (macos-13)	9m 26s
tests / py310-test-all (macos-latest)	5m 16s
tests / py311-test-all (macos-latest)	4m 44s
tests / py312-test-all (macos-latest)	4m 53s
tests / py312-test-qt (macos-latest)	4m 30s
tests / py39-test-all (windows-latest)	6m 40s
tests / py310-test-all (windows-latest)	7m 20s
tests / py311-test-all (windows-latest)	7m 18s
tests / py312-test-all (windows-latest)	6m 54s
tests / py312-test-qt (windows-latest)	6m 22s
tests / py312-test-jupyter (windows-latest)	5m 55s
	1h 33m 14s

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