Follow-up (#373): tighten vacuous positive assertion in ast_tests.rs #390

Context

In run_ast_standalone_resolves_nested_dir_corpus_correctly (crates/rskim/src/cmd/search/ast_tests.rs), the positive assertion text.contains("foo/bar.rs") || text.contains("foo") && text.contains("bar.rs") parses (Rust precedence) as contains("foo/bar.rs") || (contains("foo") && contains("bar.rs")). With the corpus foo.rs / foo/bar.rs / foobar.rs the second disjunct is ALWAYS true, so the positive check can never fail on a regression. (The two negative assertions still have teeth.)

Definition of done

Tighten the positive assertion to assert!(text.contains("foo/bar.rs")).

Origin: #373. Refs #174.