Block Bindings: Add postType to context for Post Data source

Adds a required `postType` context, which is used in the editor client side.

Props bernhard-reiter, cbravobernal.
Fixes #63994.


git-svn-id: https://develop.svn.wordpress.org/trunk@60778 602fd350-edb4-49c9-b593-d223f7449a82

Author: cbravobernal

src/wp-includes/block-bindings/post-data.php

@@ -60,7 +60,7 @@ function _register_block_bindings_post_data_source() {
 		array(
 			'label'              => _x( 'Post Data', 'block bindings source' ),
 			'get_value_callback' => '_block_bindings_post_data_get_value',
-			'uses_context'       => array( 'postId' ),
+			'uses_context'       => array( 'postId', 'postType' ), // Both are needed on the client side.
 		)
 	);
 }