Add factory_boy factory

[jambonrose]

Make testing easier for developers by providing a UserFactory (built with factory_boy).

[codecov]

Codecov Report

Merging #20 into development will not change coverage.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           development    #20   +/-   ##
==========================================
  Coverage          100%   100%           
==========================================
  Files                6      7    +1     
  Lines              148    162   +14     
  Branches            11     11           
==========================================
+ Hits               148    162   +14

Impacted Files	Coverage Δ
src/improved_user/factories.py	100% <100%> (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 5b53efd...c00286e. Read the comment docs.