Docs: Fix broken @covers tag in `_wp_post_thumbnail_context_filter(…

…)` tests.

Without the space between the tag and the "description", the tag will not be recognized and the test will not record coverage correctly.

Reference: [https://docs.phpunit.de/en/9.6/annotations.html#covers PHPUnit Manual: Annotations].

Follow-up to [55821].

Props jrf.
See #59651.

git-svn-id: https://develop.svn.wordpress.org/trunk@57105 602fd350-edb4-49c9-b593-d223f7449a82

tests/phpunit/tests/post/thumbnails.php

@@ -455,7 +455,7 @@ public function data_post_thumbnail_size_filter_complex() {
 	 *
 	 * @ticket 58212
 	 *
-	 * @covers::_wp_post_thumbnail_context_filter
+	 * @covers ::_wp_post_thumbnail_context_filter
 	 */
 	public function test_wp_post_thumbnail_context_filter_should_return_the_post_thumbnail() {
 		$this->assertSame( 'the_post_thumbnail', _wp_post_thumbnail_context_filter( 'wp_get_attachment_image' ) );