tests

Remove references to Libav #981

Job	Run time
style	14s
package-source	19s
package-wheel (macos-latest, arm64)	21m 32s
py-3.8 lib-6.0 ubuntu-latest	5m 6s
package-wheel (macos-latest, x86_64)	34m 0s
py-3.8 lib-5.1 ubuntu-latest	4m 20s
package-wheel (ubuntu-latest, aarch64)	3h 19m 21s
py-3.8 lib-5.0 ubuntu-latest	4m 3s
package-wheel (ubuntu-latest, i686)	28m 57s
py-3.8 lib-6.0 windows-latest	3m 18s
package-wheel (ubuntu-latest, x86_64)	20m 40s
py-pypy3.9 lib-5.0 ubuntu-latest	4m 24s
py-3.8 lib-5.1 windows-latest	2m 30s
package-wheel (windows-latest, AMD64)	15m 57s
py-3.8 lib-5.0 macos-latest	5m 42s
py-3.8 lib-5.0 windows-latest	3m 50s
publish	40s
	5h 54m 53s

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