Fix compatibility of interactive viewer with recent versions of Matplotlib #39

Job	Run time
test / Load tox environments	7s
test / codestyle (ubuntu-latest)	29s
test / py38-test-oldestdeps (ubuntu-latest)	54s
test / py39-test (macos-12)	1m 43s
test / py39-test (windows-latest)	1m 44s
test / py310-test (ubuntu-latest)	1m 0s
test / py311-test-viewer (macos-latest)	1m 7s
test / py312-test (windows-latest)	2m 3s
test / py313-test-devdeps (ubuntu-latest)	1m 20s
publish	0s
	10m 27s

Provide feedback