Limit --exclude to workspace packages

Previously, --exclude would start from the set of all packages
referenced in a workspace, i.e., the workspace's packages plus any
dependencies. Without --exclude, we would at most look at all the
workspace's packages, so --exclude would result in possibly verifying a
larger set of packages.

kani-driver/src/call_cargo.rs

@@ -320,7 +320,11 @@ fn packages_to_verify<'b>(
  .collect()
  } else if !args.cargo.exclude.is_empty() {
  validate_package_names(&args.cargo.exclude, &metadata.packages)?;
- metadata.packages.iter().filter(|pkg| !args.cargo.exclude.contains(&pkg.name)).collect()
+ metadata
+ .workspace_packages()
+ .into_iter()
+ .filter(|pkg| !args.cargo.exclude.contains(&pkg.name))
+ .collect()
  } else {
  match (args.cargo.workspace, metadata.root_package()) {
  (true, _) | (_, None) => metadata.workspace_packages(),