feat(post): Add count of likes

src/main/java/fr/univnantes/webandcloud/api/core/Post.java

@@ -88,4 +88,9 @@ public class Post implements WithAncestor<User> {
         return this.getAuthor().getId();
     }
 
+    @Schema(description = "Number of Users that liked this post", example = "2")
+    public Integer getNbFollowers() {
+        return getLikes() != null ? getLikes().size() : null;
+    }
+
 }