Removed unused post-content class (#4252)

* Removed unused post-content class
* Removed unused post-header class usage

blockbase/block-templates/singular.html

@@ -1,13 +1,13 @@
 <!-- wp:template-part {"slug":"header","tagName":"header"} /-->
 
-<!-- wp:group {"layout":{"inherit":true},"className":"post-header"} -->
-<div class="wp-block-group post-header">
+<!-- wp:group {"layout":{"inherit":true}} -->
+<div class="wp-block-group">
 <!-- wp:post-title /-->
 </div>
 <!-- /wp:group -->
 
 <!-- wp:group {"tagName":"main","layout":{"inherit":true}} -->
-<main class="wp-block-group post-content">
+<main class="wp-block-group">
 <!-- wp:post-featured-image {"align":"full"} /-->
 
 <!-- wp:post-content /-->

quadrat/block-templates/single.html

@@ -1,7 +1,7 @@
 <!-- wp:template-part {"slug":"header"} /-->
 
-<!-- wp:group {"className":"post-header", "tagName":"main"} -->
-<main class="wp-block-group post-header">
+<!-- wp:group {"tagName":"main"} -->
+<main class="wp-block-group">
 
 	<!-- wp:group {"className":"post-meta"} -->
 	<div class="wp-block-group post-meta">