Add `math.expm()`, `math.logm()` (#152)

* Add `math.expm()`, `math.logm()`

rename `mexp` to `expm`, keep `mexp` as alias

* set version tag to 0.4.0

Enhance the stability checks (#147)

* Check stability in all directions

* Update __about__.py

Merge pull request #146 from adtzlr/simplify-stability-check

Simplify the stability checks in `Lab` and `LabIncompressible`

Merge pull request #145 from adtzlr/update-python-versions

Update supported Python versions to 3.9+

Fixes for NumPy 2.0

Merge pull request #141 from adtzlr/update-codecov-workflow

Update the codecov-Workflow

Update __about__.py

Update __about__.py

Merge pull request #134 from adtzlr/support-python-3-11

Add support for and run tests on Python 3.11

Merge pull request #133 from adtzlr/lab-title-argument

Add optional title in `Lab(material, title=None)`