Fixes duplicate identifier issue by ignoring type checking of .d.ts files in node_modules

[scalvert]

Currently, when attempting to release, we're encountering a TS compilation error:

node_modules/@types/eslint/helpers.d.ts:1:6 - error TS2300: Duplicate identifier 'Prepend'.

1 type Prepend<Tuple extends any[], Addend> = ((_: Addend, ..._1: Tuple) => any) extends ((
       ~~~~~~~

  ../node_modules/@types/eslint/helpers.d.ts:1:6
    1 type Prepend<Tuple extends any[], Addend> = ((_: Addend, ..._1: Tuple) => any) extends (..._: infer Result) => any
           ~~~~~~~
    'Prepend' was also declared here.

node_modules/@types/eslint/lib/rules/index.d.ts:10:14 - error TS2300: Duplicate identifier 'Rule'.

10     export = Rule;
                ~~~~

  ../node_modules/@types/eslint/lib/rules/index.d.ts:10:14
    10     export = Rule;
                    ~~~~
    'Rule' was also declared here.

../node_modules/@types/eslint/helpers.d.ts:1:6 - error TS2300: Duplicate identifier 'Prepend'.

1 type Prepend<Tuple extends any[], Addend> = ((_: Addend, ..._1: Tuple) => any) extends (..._: infer Result) => any
       ~~~~~~~

  node_modules/@types/eslint/helpers.d.ts:1:6
    1 type Prepend<Tuple extends any[], Addend> = ((_: Addend, ..._1: Tuple) => any) extends ((
           ~~~~~~~
    'Prepend' was also declared here.

../node_modules/@types/eslint/lib/rules/index.d.ts:10:14 - error TS2300: Duplicate identifier 'Rule'.

10     export = Rule;
                ~~~~

  node_modules/@types/eslint/lib/rules/index.d.ts:10:14
    10     export = Rule;
                    ~~~~
    'Rule' was also declared here.


Found 4 errors.

The solution to this is to add the skipLibCheck option to the tsconfig.json. This will effectively ignore .d.ts files in node_modules, avoiding this issue.

Also adding TS linting to our workflow to avoid this in the future.

[rwjblue]

I think the CI failures were due to socketio/socket.io#4121 which is resolved now. Might need to re-roll lock file though.