Create fractional_cover_problem.py (#9973)

* Create fractional_cover_problem.py

* Update fractional_cover_problem.py

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

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

* Update fractional_cover_problem.py

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

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

* Update fractional_cover_problem.py

* Update fractional_cover_problem.py

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

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

* Update fractional_cover_problem.py

* Update fractional_cover_problem.py

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

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

* Update fractional_cover_problem.py

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

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

* Lose __eq__()

* Update fractional_cover_problem.py

* Define Item property ratio

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Christian Clauss <[email protected]>