Update doctest sol

FirePing32 · FirePing32 · commit cea6f3b26bd5 · 2021-10-24T15:07:55.000+05:30
diff --git a/project_euler/problem_078/sol1.py b/project_euler/problem_078/sol1.py
@@ -22,7 +22,7 @@
 def solution() -> str:
     """
     >>> solution()
-    55374
+    '55374'
     """
     MODULUS = 10 ** 6
     partitions = [1]
