[pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

Author: pre-commit-ci[bot]

maths/numerical_analysis/ordinary_differential_equations.py

@@ -100,4 +100,4 @@ def heuns_method(
 if __name__ == "__main__":
     import doctest
 
-    doctest.testmod()
+    doctest.testmod()