fix: make strict combinator check for missing values

[jpdenford]

Ensure strict combinator fails when required properties are missing from input object.

[jpdenford]

Thanks for the great library! 🙏
I presume that the change brings strict more inline with intended behaviour but if not then apologies for my misunderstanding.
I was also unsure of whether this change would just be a patch or something more drastic due to potential downstream breakages so I intentionally left that out.

[codecov-commenter]

Codecov Report

Merging #240 (c6a776c) into main (43cf60b) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##              main      #240   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           41        41           
  Lines          725       725           
  Branches       121       121           
=========================================
  Hits           725       725           

Impacted Files	Coverage Δ
packages/io-ts-extra/src/combinators.ts	100.00% <ø> (ø)

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[mmkal]

Thank you and sorry for the delay in merging!