MAINT: _lib: add missing f string to _deprecate_positional_args

Author: j-bowhay

scipy/_lib/deprecation.py

@@ -219,7 +219,7 @@ def warn_deprecated_args(kwargs):
             if intersection:
                 message = (f"Arguments {intersection} are deprecated, whether passed "
                            "by position or keyword. They will be removed in SciPy "
-                           "{version}. ")
+                           f"{version}. ")
                 message += custom_message
                 warnings.warn(message, category=DeprecationWarning, stacklevel=3)