Fix typings for Modal/Confirm to match their proptypes

[seryl]

Package: semantic-ui-react
Version: 0.68.1

I was seeing the following two errors when packaging with webpack:

../semantic-ui-react/dist/commonjs/addons/Confirm/Confirm.d.ts
(4,18): error TS2430: Interface 'ConfirmProps' incorrectly extends interface 'ModalProps'.
  Property 'content' is optional in type 'ConfirmProps' but required in type 'ModalProps'.

and

../semantic-ui-react/dist/commonjs/addons/Confirm/Confirm.d.ts
(4,18): error TS2430: Interface 'ConfirmProps' incorrectly extends interface 'ModalProps'.
  Property 'header' is optional in type 'ConfirmProps' but required in type 'ModalProps'.

As far as I can tell the proptypes for content and headers aren't required for modal so I've removed that restriction so that the extends will match

Note: No linter errors added and passes tests.

[codecov-io]

Codecov Report

Merging #1616 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1616   +/-   ##
=======================================
  Coverage   99.74%   99.74%           
=======================================
  Files         141      141           
  Lines        2398     2398           
=======================================
  Hits         2392     2392           
  Misses          6        6

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[layershifter]

Thanks for PR. However, there is #1611, it fixes this and many other issues.

[levithomason]

Released in [email protected].