refactor: simplify while loop logic

- Replace `removeFirst()` check with `isEmpty()` for cleaner loop condition.
- Improve code readability and maintainability.

Signed-off-by: Minecon724 <git@m724.eu>

src/main/java/eu/m724/blog/data/Post.java

@@ -60,8 +60,8 @@ public record Post(
 
         var properties = new HashMap<String, String>();
 
-        String line;
-        while ((line = lines.removeFirst()) != null) {
+        while (!lines.isEmpty()) {
+            var line = lines.removeFirst();
             var parts = line.split(" ");
 
             var key = parts[0].toLowerCase();