Remove sqlmodel dev dependency

[tcompa]

Close #373

Requires:

• https://github.com/fractal-analytics-platform/fractal-common/issues/58

[github-actions[bot]]

Coverage report

The coverage rate went from 78.74% to 78.74% :arrow_right: The branch rate is 75%.

None of the new lines are part of the tested code. Therefore, there is no coverage data about them.