Add explicit test for appending to a no-argument Pedalboard. #1214

Job	Run time
Pre-build on ubuntu-20.04 with clang	1m 49s
Pre-build on macos-13 with clang	2m 3s
Lint Python (3.12, ubuntu-20.04)	6s
Lint C++	34s
Pre-build on ubuntu-20.04 with gcc	1m 32s
Build wheel for ${{ matrix.build }}	0s
Test 1 / 8 with Python 3.12 on ubuntu-20.04	1m 15s
Test 2 / 8 with Python 3.12 on ubuntu-20.04	1m 32s
Test 3 / 8 with Python 3.12 on ubuntu-20.04	1m 26s
Test 4 / 8 with Python 3.12 on ubuntu-20.04	1m 29s
Test 5 / 8 with Python 3.12 on ubuntu-20.04	1m 26s
Test 6 / 8 with Python 3.12 on ubuntu-20.04	1m 26s
Test 7 / 8 with Python 3.12 on ubuntu-20.04	1m 28s
Test 8 / 8 with Python 3.12 on ubuntu-20.04	1m 25s
Test with Python 3.7 + Address Sanitizer	2m 33s
Test with Python 3.8 + Address Sanitizer	2m 33s
Test with Python 3.9 + Address Sanitizer	2m 33s
Test with Python 3.10 + Address Sanitizer	2m 34s
Test with Python 3.11 + Address Sanitizer	2m 33s
Test with Python 3.7 on macos-13	2m 16s
Test with Python 3.8 on macos-13	2m 12s
Test with Python 3.9 on macos-13	2m 17s
Test with Python 3.10 on macos-13	2m 9s
Test with Python 3.11 on macos-13	2m 12s
Test with Python 3.12 on macos-13	2m 15s
Test with Python 3.7 on ubuntu-20.04	2m 15s
Test with Python 3.8 on ubuntu-20.04	2m 16s
Test with Python 3.9 on ubuntu-20.04	2m 15s
Test with Python 3.10 on ubuntu-20.04	2m 16s
Test with Python 3.11 on ubuntu-20.04	2m 16s
Test with Python 3.12 on ubuntu-20.04	2m 16s
Test with Python 3.12 on windows-latest	1m 58s
Upload wheels to PyPI	1s
	59m 11s

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