feat(expect): add more methods

tests/Expect/toBeBool.php

@@ -0,0 +1,16 @@
+<?php
+
+use PHPUnit\Framework\ExpectationFailedException;
+
+test('pass', function () {
+    expect(true)->toBeBool();
+    expect(0)->not->toBeBool();
+});
+
+test('failures', function () {
+    expect(null)->toBeBool();
+})->throws(ExpectationFailedException::class);
+
+test('not failures', function () {
+    expect(false)->not->toBeBool();
+})->throws(ExpectationFailedException::class);