add deque __bool__ method (#2931)

Adds deque.bool

vm/src/stdlib/collections.rs

@@ -472,6 +472,11 @@ mod _collections {
             self.borrow_deque().len()
         }
 
+        #[pymethod(magic)]
+        fn bool(&self) -> bool {
+            !self.borrow_deque().is_empty()
+        }
+
         #[pymethod(magic)]
         fn iadd(
             zelf: PyRef<Self>,