Fix test expectation for getMaxDifference with empty inputs

Co-authored-by: renemadsen <76994+renemadsen@users.noreply.github.com>

Author: Copilot

eform-client/src/app/plugins/modules/time-planning-pn/components/plannings/time-planning-actions/workday-entity/workday-entity-dialog.component.spec.ts

@@ -242,8 +242,8 @@ describe('WorkdayEntityDialogComponent', () => {
         expect(result).toBe('2:0'); // 2 hours to midnight
       });
 
-      it('should return 00:00 for invalid inputs', () => {
-        expect(component.getMaxDifference('', '')).toBe('00:00');
+      it('should return 0:0 for invalid inputs', () => {
+        expect(component.getMaxDifference('', '')).toBe('0:0');
       });
 
       it('should handle times with minutes', () => {