feat(ci): Hash project euler solutions (#4411)

* hash project euler solutions

* fix errors

* Return missing annotation

* Fix typo

* Extract variable to shorten excessively long line

* Update scripts/validate_solutions.py

* Update scripts/validate_solutions.py

* Simplify with str.encode()

* PEP 585: type hinting generics in standard collections;

* str().encode()

* Texas two step to placate black, flake8, mypy

Co-authored-by: Andrii Siriak <siryaka@gmail.com>
Co-authored-by: Christian Clauss <cclauss@me.com>