Give parsing ability to datetime types

[antonagestam]

Closes #86.

Todo

• Update documentation.
• Address issue mentioned in Make TZAware.parse use dateutil #86 with regards to infinity.
• Test that TZAware and TZNaive can be used without python-dateutil installed, as long as no attempts to parse strings are made.
• Address coverage.
• Coverage is no longer incremental within a run, gives wrong results ...

[codecov-commenter]

Codecov Report

Merging #234 (45571c9) into main (1eee5f3) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##              main      #234   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           24        26    +2     
  Lines          821       859   +38     
  Branches       172       175    +3     
=========================================
+ Hits           821       859   +38     

Impacted Files	Coverage Δ
src/phantom/__init__.py	100.00% <100.00%> (ø)
src/phantom/_base.py	100.00% <100.00%> (ø)
src/phantom/bounds.py	100.00% <100.00%> (ø)
src/phantom/datetime.py	100.00% <100.00%> (ø)
src/phantom/errors.py	100.00% <100.00%> (ø)
src/phantom/ext/phonenumbers.py	100.00% <100.00%> (ø)
src/phantom/iso3166.py	100.00% <100.00%> (ø)

📣 We’re building smart automated test selection to slash your CI/CD build times. Learn more