fix: add predicate for isBoolean

[heyqbnk]

Description

Hey, I have found one little bug in types. isBoolean should have a predicate which states, that value is boolean.

Minimal code-snippet showcasing the problem
Here is a simple example. TypeScript will keep thinking, val is 123, but isBoolean should make him think, its boolean.

function getRandomType(): string | number | boolean {
  return 'No random in our life';
}

const val = getRandomType(); // val here is string, or number, or boolean

if (isBoolean(val)) {
  const someAnotherVal = val; // someAnotherVal will have type string, or number, or boolean, but it should be clear boolean
}

Expected behavior

TypeScript knows that value has type boolean.

Actual behavior

isBoolean returns boolean value without predicate, so, it does not say anything for TypeScript.

[NoNameProvided]

I think this is already in 0.14.0.

[github-actions]

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