Fix identical creation dates in tests

Author: LaurentTreguier

src/main/java/app/fyreplace/api/data/dev/DataSeeder.java

@@ -112,6 +112,7 @@ public User createUser(
             user.persist();
         }
 
+        sleep();
         return user;
     }
 
@@ -135,6 +136,7 @@ public Post createPost(final User author, final String text, final boolean publi
             post.publish(postsStartingLife, anonymous);
         }
 
+        sleep();
         return post;
     }
 
@@ -146,6 +148,15 @@ public Comment createComment(final User author, final Post post, final String te
         comment.post = post;
         comment.text = text;
         comment.persist();
+        sleep();
         return comment;
     }
+
+    private void sleep() {
+        try {
+            Thread.sleep(1L);
+        } catch (InterruptedException e) {
+            throw new RuntimeException(e);
+        }
+    }
 }