Moptipy

Some minor bug fixes and improvements for signed permutations.

Signed permutations can, in theory, also only include the same value (many times) because they can be, well, signed.
We adopted the corresponding class and operators accordingly.

Also, temporarily, flake8 is deactivated in the build because it has some version incompatibility issue.
Hopefully that will be fixed soon.

We added the [signed permutations](https://thomasweise.github.io/moptipy/moptipy.spaces.html#module-moptipy.spaces.signed_permutations) space as well as [corresponding tests](https://thomasweise.github.io/moptipy/moptipy.tests.html#module-moptipy.tests.on_signed_permutations) as well as a [nullary](https://thomasweise.github.io/moptipy/moptipy.operators.signed_permutations.html#module-moptipy.operators.signed_permutations.op0_shuffle_and_flip) and a [unary](https://thomasweise.github.io/moptipy/moptipy.operators.signed_permutations.html#module-moptipy.operators.signed_permutations.op1_swap_2_or_flip) operator.

minor improvements and bug fixes

- better doctests for nputils
- more consistent behavior of some nputils functions
- caching of JSSP instances
- slightly better documentation
- added type annotations here and there

We added py.typed to allow typecheckers like mypy to check types when using moptipy.

pdfo in [version 1.3](https://pypi.org/project/pdfo/1.3/) uses `np.int`, which was deprecated and now [removed](https://github.com/numpy/numpy/pull/22607), from numpy [version 1.24.0](https://pypi.org/project/numpy/1.24.0/); i.e., deprecation of `np.int` has [expired](https://numpy.org/doc/1.24/release/1.24.0-notes.html#expired-deprecations).
This causes pdfo to throw an exception, as I detailed in their [issue 55](https://github.com/pdfo/pdfo/issues/55).
The pdfo developers will very soon fix this.
But for now, the newest versions of pdfo and numpy do not work together.
We implemented a temporary fix that simply lets our pdfo wrapper perform a random sample step and then quit if this version incompatibility is detected.
So right now, if you install our package, the [pdfo optimizer][(https://thomasweise.github.io/moptipy/moptipy.algorithms.so.vector.html#module-moptipy.algorithms.so.vector.pdfo) will not work.
But it will be fixed soon by the pdfo developers anyway - they already patched it in their [code base](https://github.com/pdfo/pdfo/commit/508369b372367d4549337c9cba62a5e46ae0e53d).

We also introduced a couple of minor fixes and improvements and stepped the dependency versions.

- BugFix in [Op1SwapTryN](https://thomasweise.github.io/moptipy/moptipy.operators.permutations.html#module-moptipy.operators.permutations.op1_swap_try_n) Operator: It swapped one element too many
- Better tests for detecting the above behavior