chore: update typescript to 4.3-rc

[bradzacher]

Ref #3272

[typescript-eslint]

Thanks for the PR, @bradzacher!

typescript-eslint is a 100% community driven project, and we are incredibly grateful that you are contributing to that community.

The core maintainers work on this in their personal time, so please understand that it may not be possible for them to review your work immediately.

Thanks again!

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[codecov]

Codecov Report

Merging #3426 (ecc0ed4) into master (02acc4f) will decrease coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #3426      +/-   ##
==========================================
- Coverage   92.68%   92.66%   -0.02%     
==========================================
  Files         318      318              
  Lines       11100    11100              
  Branches     3152     3152              
==========================================
- Hits        10288    10286       -2     
- Misses        361      362       +1     
- Partials      451      452       +1     

Flag	Coverage Δ
unittest	92.66% <100.00%> (-0.02%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
packages/eslint-plugin/src/rules/dot-notation.ts	92.59% <ø> (ø)
packages/typescript-estree/src/convert.ts	98.24% <100.00%> (ø)
packages/eslint-plugin/src/util/types.ts	81.18% <0.00%> (-1.08%)	⬇️