Fix import paths to official ones #132

Job	Run time
Run linters	36s
Build docs & run doctests	29s
Verify dev env (ubuntu-latest)	16s
Verify dev env (windows-latest)	1m 49s
Tests on 3.8	56s
Verify dev env (macos-latest)	27s
Tests on 3.9	1m 5s
Tests on 3.10	1m 0s
Type-check package	26s
Tests on 3.11	55s
Tests on 3.12	1m 15s
Tests on pypy-3.8	1m 11s
Tests on pypy-3.9	1m 13s
Combine & check coverage	9s
required-checks-pass	1s
	11m 48s

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