Required new line before `typeof`

[ruiquelhas]

Currently, when the module tries to lint itself, we get the following error:

Keyword `typeof` should have an empty line above it at ./src/rules/require-should-assertion-execution.js :
    14 |const Assertion = should.Assertion.prototype;
    15 |const assertions = Object.keys(Assertion);
    16 |const chains = Object.keys(Assertion).filter(key => typeof Assertion[key] !== 'function');
-----------------------------------------------------------^
    17 |
    18 |/**

As far as I am aware, there is no good reason for this requirement, so we should just remove it.