* feat(project_euler): add solution to problem 60
* fix(project_euler): fix var name and type hints
* chore(project_euler): update directory to include problem 60 solution
* chore(directory): update DIRECTORY.md to keep it about current files
* fix(project_euler): add doctest to search
* updating DIRECTORY.md
* updating DIRECTORY.md
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Co-authored-by: AksharGoyal <AksharGoyal@users.noreply.github.com>
