Update can/interfaces/slcan.py

Fix black formatter

Author: felixdivo

can/interfaces/slcan.py

@@ -256,7 +256,9 @@ def fileno(self) -> int:
         try:
             return self.serialPortOrig.fileno()
         except io.UnsupportedOperation:
-            raise NotImplementedError("fileno is not implemented using current CAN bus on this platform")
+            raise NotImplementedError(
+                "fileno is not implemented using current CAN bus on this platform"
+            )
 
     def get_version(
         self, timeout: Optional[float]