Fix bool return type in stubs

[Jeckerson]

Example from Phalcon:

/**
     * Sets the dirty state of the object using one of the DIRTY_STATE_
     * constants
     *
     * @param int $dirtyState
     * @return 0|ModelInterface
     */
    public function setDirtyState(int $dirtyState);

Should be

/**
     * Sets the dirty state of the object using one of the DIRTY_STATE_
     * constants
     *
     * @param int $dirtyState
     * @return bool|ModelInterface
     */
    public function setDirtyState(int $dirtyState);