Pyupgrade to Python 3.9 (#4718)

* Pyupgrade to Python 3.9

* updating DIRECTORY.md

Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>

project_euler/problem_049/sol1.py

@@ -132,7 +132,7 @@ def solution():
     for seq in passed:
         answer.add("".join([str(i) for i in seq]))
 
-    return max([int(x) for x in answer])
+    return max(int(x) for x in answer)
 
 
 if __name__ == "__main__":