Media: Correct `since` annotation for adding the `caption_id` attribute.

Introduced in [42704]
Fixes #34595.
Built from https://develop.svn.wordpress.org/trunk@44548


git-svn-id: http://core.svn.wordpress.org/trunk@44379 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/media.php

@@ -1498,7 +1498,7 @@ add_shortcode( 'caption', 'img_caption_shortcode' );
  *
  * @since 2.6.0
  * @since 3.9.0 The `class` attribute was added.
- * @since 5.0.0 The `caption_id` attribute was added.
+ * @since 5.1.0 The `caption_id` attribute was added.
  *
  * @param array  $attr {
  *     Attributes of the caption shortcode.

wp-includes/version.php

@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.1-alpha-44547';
+$wp_version = '5.1-alpha-44548';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.