fix(types/integer): use Number.isInteger for validating a value is an integer or not

[yoshinorin]

This PR is fix for TS2362 & TS2322 errors. We are facing TS2362 & TS2322 errors when we run npm run eslint.

> warehouse@5.0.0 preeslint
> npm run clean && npm run build

> warehouse@5.0.0 clean
> tsc -b --clean

> warehouse@5.0.0 build
> tsc -b

Error: src/types/integer.ts(32,9): error TS2362: The left-hand side of an arithmetic operation must be of type 'any', 'number', 'bigint' or an enum type.
Error: src/types/integer.ts(36,5): error TS2322: Type 'unknown' is not assignable to type 'number'.
Error: Process completed with exit code 1.

Thank you :)