Only flag flake8-trio rule when trio is present (#8550)

## Summary

Hoping to avoid some false positives by narrowing the scope of
https://github.com/astral-sh/ruff/pull/8534.

crates/ruff_python_semantic/src/model.rs

@@ -1207,6 +1207,16 @@ impl<'a> SemanticModel<'a> {
         exceptions
     }
 
+    /// Return `true` if the module at the given path was seen anywhere in the semantic model.
+    /// This includes both direct imports (`import trio`) and member imports (`from trio import
+    /// TrioTask`).
+    pub fn seen(&self, module: &[&str]) -> bool {
+        self.bindings
+            .iter()
+            .filter_map(Binding::as_any_import)
+            .any(|import| import.call_path().starts_with(module))
+    }
+
     /// Generate a [`Snapshot`] of the current semantic model.
     pub fn snapshot(&self) -> Snapshot {
         Snapshot {