Find _inject.abi3.so relative to _memray.*.so

With an editable `scikit-build-core` install, shared libraries are not
in the same directory as Python files, so we can no longer locate it
relative to `__init__.py`.

Signed-off-by: Matt Wozniski <mwozniski@bloomberg.net>

Author: godlygeek

src/memray/commands/attach.py

@@ -130,7 +130,7 @@ def deactivate_because_timer_elapsed():
 
 def inject(debugger: str, pid: int, port: int, verbose: bool) -> str | None:
     """Executes a file in a running Python process."""
-    injecter = pathlib.Path(memray.__file__).parent / "_inject.abi3.so"
+    injecter = pathlib.Path(memray._memray.__file__).parent / "_inject.abi3.so"
     assert injecter.exists()
 
     gdb_cmd = [