Remove a whitespace in B004 message (#2991)

crates/ruff/src/rules/flake8_bugbear/rules/unreliable_callable_check.rs

@@ -13,7 +13,7 @@ impl Violation for UnreliableCallableCheck {
     #[derive_message_formats]
     fn message(&self) -> String {
         format!(
-            " Using `hasattr(x, '__call__')` to test if x is callable is unreliable. Use \
+            "Using `hasattr(x, '__call__')` to test if x is callable is unreliable. Use \
              `callable(x)` for consistent results."
         )
     }