Remove pandas version restriction

[Thomas Heavey]

Describe the problem.
There are bug fixes and features available in newer versions of pandas that I would like to have access to.
In my non-thorough testing, this package works just fine with newer versions of pandas (1.2.0).

Describe the solution you'd like
Testing of the package with the version constraint removed followed by removing the version restriction.

Describe alternatives you've considered
I currently just have multiple environments with different package versions to work around this restriction.
If there are issues found, the restriction is reasonable to remain, but I would be willing to help fix issues that are found.

Are you willing to contribute
Yes

Additional context
Because pandas follows semantic versioning, there should be no breaking changes going from 1.0 to 1.2 unless you are relying on some internal implementation details in pandas or a bug.

[Chris Ruppelt]

Thanks for reaching out theavey! This is great advice and we are looking into this internally.

[Thomas Heavey]

https://iscinumpy.dev/post/bound-version-constraints/

On a related note, we had some issues internally when #211 was merged, which included a quite restrictive matplotlib version specification

[AnastasiyaB]

Thanks Tom, will look into that one too.

[Thomas Heavey]

This seems fixed by #221

db0156e#diff-60f61ab7a8d1910d86d9fda2261620314edcae5894d5aaa236b821c7256badd7R71