Crater skips repositories with a Cargo.toml but not Cargo.lock

[Aaron1011]

When data/github.csv is read, only repositories with both a Cargo.toml and a Cargo.lock are tested:

crater/src/crates/sources/github.rs

Lines 44 to 47 in dcc5456

	// Only import repos with a Cargo.toml or Cargo.lock
	if !line.has_cargo_toml || !line.has_cargo_lock {
	continue;
	}

Based on the comment, it looks like the intention was to test repositories with just a Cargo.lock or Cargo.toml as well.

This resulted in a Crater run failing to detect a regression in rust-lang/rust#77718. While Crater cannot be expected to catch all regressions, I think it would be a good idea to test these kinds of repositories. Hopefully, doing so doesn't lead to a significant increase in job run time.

[pietroalbini]

The intention of that condition was to filter out libraries already published on crates.io, as there is usually little point in testing multiple versions of the same library. I think it's fine to remove the condition if we implement a more advanced one that still filters out crates published on crates.io.