build: update eslint

[WikiRik]

ESLint updated and made sure it only runs on the CI check for Node 14. All fixes were auto-updated or ignored for now.
The following are ignored:

• src/lib/alpha.js (no-misleading-character-class on lines 32 and 38, I don't speak Arabic but these might be false positives)
• src/lib/isIdentityCard.js (max-len on lines 24 and 309, this can be refactored)
• src/lib/util/merge.js (default-param-last on line 2, this can be refactored)
• test/client-side.js (import/no-unresolved and import/extensions on line 3 and 4, these are fixed after running npm run build)
• test/exports.js (import/no-unresolved and import/extensions on line 3, these are fixed after running npm run build)

The ignored files that can be refactored will be done as a different PR to keep this PR relatively small.

I didn't notice #1869 before, but I think that this PR is still useful to reduce the changes for the other PR.

Once we run CI on Node 12 and up we can put npm run lint back to the pretest script and remove the additional test, although I like that the tests are not dependent on the linter.

Checklist

• PR contains only changes related; no stray files, etc.
• README updated (where applicable) Not applicable
• Tests written (where applicable) Not applicable

[codecov]

Codecov Report

Merging #1894 (f048a4c) into master (f055c11) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##            master     #1894   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files          102       102           
  Lines         2072      2071    -1     
  Branches       472       472           
=========================================
- Hits          2072      2071    -1     

Impacted Files	Coverage Δ
src/lib/alpha.js	100.00% <ø> (ø)
src/lib/isDataURI.js	100.00% <ø> (ø)
src/lib/isEAN.js	100.00% <ø> (ø)
src/lib/isHSL.js	100.00% <ø> (ø)
src/lib/isIMEI.js	100.00% <ø> (ø)
src/lib/isURL.js	100.00% <ø> (ø)
src/lib/util/merge.js	100.00% <ø> (ø)
src/lib/isBase64.js	100.00% <100.00%> (ø)
src/lib/isCurrency.js	100.00% <100.00%> (ø)
src/lib/isDate.js	100.00% <100.00%> (ø)
... and 15 more

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[profnandaa]

Thanks for your suggestion but I think this change is not necessary for now. We can hold off on it for now.

[WikiRik]

Sure, thanks for looking at it!