Make "number of puzzles solved" on the profile page include only already released puzzles

Description

On the user's profile page, puzzles created by the user, but not yet released to the public (or even not assigned to a date) are counted towards the total number of puzzles solved by the user. This merge request solves this issue.

Checklist

• I have added tests for functionality I added and/or changed
• I have changed the database schema
  • I have added migrations
• I have added the required changelog entries
• I have run my branch and ensured all functionality is still working as intended

src/main/java/nl/tudelft/pupple/model/labracore/PupplePerson.java

@@ -59,7 +59,10 @@ public class PupplePerson {
 	private Set<Puzzle> createdPuzzles = new HashSet<>();
 
 	public long numberOfPuzzlesSolved() {
-		return this.puzzleAttempts.stream().filter(p -> p.getSolved()).count();
+		return this.puzzleAttempts.stream().filter(p -> {
+			LocalDate dayUsed = p.getPuzzle().getDayUsed();
+			return p.getSolved() && dayUsed != null && !dayUsed.isAfter(LocalDate.now());
+		}).count();
 	}
 
 	public long numberOfPuzzlesFeatured() {