memray's wheels contain the ./memray/_memray/ directory

[sarahmonod]

Memray's wheels currently contain a ./memray/_memray/ directory (see memray-1.17.2-cp310-cp310-manylinux_2_12_x86_64.manylinux2010_x86_64.whl for instance). This contains some of Memray's source code. This is harmless, but not necessary or useful, and we should remove it by telling setuptools that memray/_memray/ is not a package.