Editor: Ensure that timezone.offset passed to @wordpress/date is a float

Fixes inconsistent type of `timezone.offset` passed to `@wordpress/date`. It
should always be a float, never a string.

Props talldanwp.
Fixes #56459.

Built from https://develop.svn.wordpress.org/trunk@53956


git-svn-id: http://core.svn.wordpress.org/trunk@53515 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/script-loader.php

@@ -416,7 +416,7 @@ function wp_default_packages_inline_scripts( $scripts ) {
 						'datetimeAbbreviated' => __( 'M j, Y g:i a' ),
 					),
 					'timezone' => array(
-						'offset' => get_option( 'gmt_offset', 0 ),
+						'offset' => (float) get_option( 'gmt_offset', 0 ),
 						'string' => $timezone_string,
 						'abbr'   => $timezone_abbr,
 					),