Add variable time-stretching and pitch-shifting. #1124

Job	Run time
Lint C++	21s
Pre-build on ubuntu-20.04 with clang	1m 49s
Pre-build on macos-13 with clang	1m 46s
Lint Python (3.12, ubuntu-20.04)	6s
Pre-build on ubuntu-20.04 with gcc	1m 19s
Build wheel for ${{ matrix.build }}	0s
Test 1 / 8 with Python 3.12 on ubuntu-20.04	1m 30s
Test 2 / 8 with Python 3.12 on ubuntu-20.04	1m 22s
Test 3 / 8 with Python 3.12 on ubuntu-20.04	1m 47s
Test 4 / 8 with Python 3.12 on ubuntu-20.04	1m 17s
Test 5 / 8 with Python 3.12 on ubuntu-20.04	1m 12s
Test 6 / 8 with Python 3.12 on ubuntu-20.04	1m 21s
Test 7 / 8 with Python 3.12 on ubuntu-20.04	1m 24s
Test 8 / 8 with Python 3.12 on ubuntu-20.04	1m 23s
Test with Python 3.7 on macos-13	10m 34s
Test with Python 3.8 on macos-13	10m 39s
Test with Python 3.9 on macos-13	10m 6s
Test with Python 3.10 on macos-13	10m 3s
Test with Python 3.11 on macos-13	9m 49s
Test with Python 3.12 on macos-13	9m 16s
Test with Python 3.7 on ubuntu-20.04	5m 38s
Test with Python 3.8 on ubuntu-20.04	6m 34s
Test with Python 3.9 on ubuntu-20.04	5m 53s
Test with Python 3.10 on ubuntu-20.04	6m 16s
Test with Python 3.11 on ubuntu-20.04	5m 59s
Test with Python 3.12 on ubuntu-20.04	5m 44s
Test with Python 3.12 on windows-latest	10m 32s
Test with Python 3.7 + Address Sanitizer	8m 6s
Test with Python 3.8 + Address Sanitizer	8m 54s
Test with Python 3.9 + Address Sanitizer	9m 8s
Test with Python 3.10 + Address Sanitizer	8m 50s
Test with Python 3.11 + Address Sanitizer	8m 41s
Upload wheels to PyPI	0s
	2h 47m 19s

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