Hot fix for string interpolation in message.

Closes 2069.

Author: fselmo

newsfragments/2069.bugfix.rst

@@ -0,0 +1 @@
+Hot fix for a string interpolation issue in message when BadFunctionCallOutput is raised for call_contract_function()

web3/contract.py

@@ -1524,8 +1524,8 @@ def call_contract_function(
             )
         else:
             msg = (
-                "Could not decode contract function call {function_identifier} "
-                "return data {return_data!r} for output_types {output_types}"
+                f"Could not decode contract function call {function_identifier} "
+                f"return data {return_data!r} for output_types {output_types}"
             )
         raise BadFunctionCallOutput(msg) from e