[mypy] fix type annotations for project euler problem080/sol1

Author: pikulet

project_euler/problem_080/sol1.py

@@ -26,12 +26,13 @@ def solution() -> int:
         sqrt_number = number.sqrt(decimal_context)
         if len(str(sqrt_number)) > 1:
             answer += int(str(sqrt_number)[0])
-            sqrt_number = str(sqrt_number)[2:101]
-            answer += sum(int(x) for x in sqrt_number)
+            sqrt_number_str = str(sqrt_number)[2:101]
+            answer += sum(int(x) for x in sqrt_number_str)
     return answer
 
 
 if __name__ == "__main__":
     import doctest
 
     doctest.testmod()
+    print(f"{solution() = }")