Tests

Refactor gx.Track and gx.Multitrack #810

Job	Run time
cpython (3.7)	39s
cpython (3.8)	24s
cpython (3.9)	22s
cpython (3.10)	33s
cpython (3.11)	25s
cpython-lxml (3.7)	32s
cpython (3.12)	44s
cpython-lxml (3.8)	33s
cpython-lxml (3.9)	39s
cpython-lxml (3.10)	36s
cpython-lxml (3.11)	35s
cpython-lxml (3.12)	55s
static-tests (3.9)	31s
pypy (pypy-3.7)	40s
pypy (pypy-3.8)	32s
pypy (pypy-3.9)	36s
pypy (pypy-3.10)	36s
Build and publish to PyPI and TestPyPI	0s
	9m 52s

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