Rename "derive" as "restrict"

[ewjoachim]

Successful PR Checklist:

• Tests
  • (not applicable?)
• Documentation
  • (not applicable?)

[codecov]

Codecov Report

Merging #8 (d25970e) into master (f484bd7) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##            master        #8   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            3         3           
  Lines          143       143           
  Branches        10        10           
=========================================
  Hits           143       143           

Impacted Files	Coverage Δ
pypitoken/token.py	100.00% <100.00%> (ø)

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