Delete spurious pytest cache file

.pytest_cache/v/cache/lastfailed

-{
-  "test/test_matrixgen.py::test_p2p_direct[ctx_getter=<context factory for <pyopencl.Device 'pthread-Intel(R) Core(TM) i7-4712HQ CPU @ 2.30GHz' on 'Portable Computing Language' at 0x55b29f3ad210>>-False]": true,
-  "test/test_matrixgen.py::test_p2p_direct[ctx_getter=<context factory for <pyopencl.Device 'pthread-Intel(R) Core(TM) i7-4712HQ CPU @ 2.30GHz' on 'Portable Computing Language' at 0x55b29f3ad210>>-True]": true
-}
\ No newline at end of file