ENH: add dropna keyword to Unique

[martinfleis]

Closes #279

[codecov]

Codecov Report

Merging #280 (dfb04b7) into main (9d0096a) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main     #280   +/-   ##
=======================================
  Coverage   95.70%   95.70%           
=======================================
  Files          12       12           
  Lines        2540     2540           
=======================================
  Hits         2431     2431           
  Misses        109      109           

Impacted Files	Coverage Δ
momepy/diversity.py	97.70% <100.00%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 9d0096a...dfb04b7. Read the comment docs.

[martinfleis]

The failure of the docs is fixed in geopandas master. Merging.