build: fix location of multiple exec artifacts

[davidhewitt]

Closes #281

The call to _find_cargo_artifacts returned a generator, and then we searched this in a loop, causing unreliable results (e.g. the generator can be empty on the second turn of the loop). Changed _find_cargo_artifacts to return a list.

[davidhewitt]

The line which searched the artefacts was below, but it's called in a loop, which is why the generator was a problem.

setuptools-rust/setuptools_rust/build.py

Lines 259 to 263 in 6d87a5b

	artifact_path = next(
	artifact
	for artifact in artifacts
	if Path(artifact).with_suffix("").name == name
	)

[messense]

Looks good to me!