Explicit arguments for simpson

[BerriesLab]

References to issues or other PRs

Describe the proposed changes

self._weights = scipy.integrate.simpson(y=identity, x=X.grid_points[0])

should replace

self._weights = scipy.integrate.simpson(identity, X.grid_points[0])

in FPCA._fit_grid (currently line 351 in "Functional Principal Component Analysis Module.")

By not specifying x and y, simpson() returns the error:

TypeError: simpson() takes 1 positional argument but 2 were given

Additional information

Checklist before requesting a review

• I have performed a self-review of my code
• The code conforms to the style used in this package
• The code is fully documented and typed (type-checked with Mypy)
• I have added thorough tests for the new/changed functionality

[vnmabus]

Thanks for the fix!

The tests pass and the change is non-controversial, so I will merge it.