Add missing TestCase import in CollapseTest and OffcanvasTest files. (#240)

Author: terabytesoftw

tests/CollapseTest.php

@@ -6,6 +6,7 @@
 
 use InvalidArgumentException;
 use PHPUnit\Framework\Attributes\Group;
+use PHPUnit\Framework\TestCase;
 use Yiisoft\Yii\Bootstrap5\Collapse;
 use Yiisoft\Yii\Bootstrap5\Toggler;
 use Yiisoft\Yii\Bootstrap5\Tests\Support\Assert;

tests/OffcanvasTest.php

@@ -6,6 +6,7 @@
 
 use InvalidArgumentException;
 use PHPUnit\Framework\Attributes\Group;
+use PHPUnit\Framework\TestCase;
 use Yiisoft\Html\Tag\Div;
 use Yiisoft\Yii\Bootstrap5\Dropdown;
 use Yiisoft\Yii\Bootstrap5\DropdownItem;