Add Field aliases

[rossmacarthur]

Add the following Field aliases:

• Boolean <-> Bool
• Dictionary <-> Dict
• Integer <-> Int
• String <-> Str

Resolves #11

[codecov-io]

Codecov Report

Merging #14 into master will not change coverage.
The diff coverage is 100%.

@@          Coverage Diff          @@
##           master    #14   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files           7      7           
  Lines         395    399    +4     
=====================================
+ Hits          395    399    +4

Impacted Files	Coverage Δ
serde/field/__init__.py	100% <100%> (ø)	⬆️

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