Build/Test Tooling: Use `assertSame()` in `WP_Date_Query` tests.

Change from `assertEquals()` to `assertSame()`. Why? To ensure both the return value and data type match the expected results.

Follow-up to [54530].

Props costdev, peterwilsoncc, mukesh27, ankitmaru.
See #56800.
Built from https://develop.svn.wordpress.org/trunk@55465


git-svn-id: http://core.svn.wordpress.org/trunk@54998 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/version.php

@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.2-beta4-55464';
+$wp_version = '6.2-beta4-55465';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.