Update separator block HTML in tests

With this commit, the expected HTML for the separator block is updated to reflect recent changes from #38428.

This is done so that the tests pass as expected.

packages/react-native-editor/__device-tests__/gutenberg-editor-block-insertion-2.test.js

@@ -35,7 +35,7 @@ describe( 'Gutenberg Editor tests for Block insertion 2', () => {
 <!-- /wp:heading -->
 
 <!-- wp:separator -->
-<hr class="wp-block-separator"/>
+<hr class="wp-block-separator has-alpha-channel-opacity"/>
 <!-- /wp:separator -->
 
 <!-- wp:list -->
@@ -66,7 +66,7 @@ describe( 'Gutenberg Editor tests for Block insertion 2', () => {
 <!-- /wp:image -->
 
 <!-- wp:separator -->
-<hr class="wp-block-separator"/>
+<hr class="wp-block-separator" has-alpha-channel-opacity/>
 <!-- /wp:separator -->
 
 <!-- wp:list -->
@@ -89,7 +89,7 @@ describe( 'Gutenberg Editor tests for Block insertion 2', () => {
 <!-- /wp:image -->
 
 <!-- wp:separator -->
-<hr class="wp-block-separator"/>
+<hr class="wp-block-separator" has-alpha-channel-opacity/>
 <!-- /wp:separator -->
 
 <!-- wp:list -->
@@ -116,7 +116,7 @@ describe( 'Gutenberg Editor tests for Block insertion 2', () => {
 <!-- /wp:image -->
 
 <!-- wp:separator -->
-<hr class="wp-block-separator"/>
+<hr class="wp-block-separator" has-alpha-channel-opacity/>
 <!-- /wp:separator -->
 
 <!-- wp:list -->