Add `#[track_caller]` for check_assist_by_label

crates/ide-assists/src/tests.rs

diff --git a/crates/ide-assists/src/tests.rs b/crates/ide-assists/src/tests.rs
index 3e422ae..c0637a7 100644
--- a/crates/ide-assists/src/tests.rs
+++ b/crates/ide-assists/src/tests.rs
@@ -180,6 +180,7 @@
 
 // There is no way to choose what assist within a group you want to test against,
 // so this is here to allow you choose.
+#[track_caller]
 pub(crate) fn check_assist_by_label(
     assist: Handler,
     #[rust_analyzer::rust_fixture] ra_fixture_before: &str,