tests

Remove missing classes #108

Job	Run time
Tests (8.1, ubuntu-latest, prefer-lowest)	25s
Tests (8.1, ubuntu-latest, prefer-stable)	25s
Tests (8.1, macos-latest, prefer-lowest)	1m 26s
Tests (8.1, macos-latest, prefer-stable)	1m 30s
Tests (8.1, windows-latest, prefer-lowest)	53s
Tests (8.1, windows-latest, prefer-stable)	52s
Tests (8.2, ubuntu-latest, prefer-lowest)	24s
Tests (8.2, ubuntu-latest, prefer-stable)	23s
Tests (8.2, macos-latest, prefer-lowest)	1m 43s
Tests (8.2, macos-latest, prefer-stable)	1m 25s
Tests (8.2, windows-latest, prefer-lowest)	47s
Tests (8.2, windows-latest, prefer-stable)	53s
Tests (8.3, ubuntu-latest, prefer-lowest)	21s
Tests (8.3, ubuntu-latest, prefer-stable)	22s
Tests (8.3, macos-latest, prefer-lowest)	1m 26s
Tests (8.3, macos-latest, prefer-stable)	1m 46s
Tests (8.3, windows-latest, prefer-lowest)	45s
Tests (8.3, windows-latest, prefer-stable)	43s
	16m 29s

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