Adds __new__ method, removes init method

[spacether]

Adds __new__ method, removes __init__ method

[codecov]

Codecov Report

Merging #263 (f93d14e) into master (5b289b3) will not change coverage.
The diff coverage is 100.00%.

❗ Current head f93d14e differs from pull request most recent head c85f8d7. Consider uploading reports for the commit c85f8d7 to get more accurate results

@@            Coverage Diff            @@
##            master      #263   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            1         1           
  Lines           55        59    +4     
=========================================
+ Hits            55        59    +4     

Flag	Coverage Δ
3.10	100.00% <100.00%> (?)
3.11	100.00% <100.00%> (?)
3.12	?
3.12.0-rc.1	100.00% <100.00%> (?)
3.8	100.00% <100.00%> (?)
3.9	100.00% <100.00%> (?)

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Files	Coverage Δ
immutabledict/__init__.py	100.00% <100.00%> (ø)

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