Replace all old remaining schedule links for tdf3

Replace schedule.html by https://tdf3.schedule.cttue.de/tdf3/schedule/

tdf3/en/participate.html

@@ -15,7 +15,7 @@
             <nav class="navigationbar">
                 <a href="index.html" class="nav-button">Main Page</a>
                 <a href="participate.html" class="nav-button inactive">Participate</a>
-                <a href="schedule.html" class="nav-button">Schedule</a>
+                <a href="https://tdf3.schedule.cttue.de/tdf3/schedule/" class="nav-button">Schedule</a>
                 <a href="recap.html" class="nav-button">Recap</a>
             </nav>
 

tdf3/en/recap.html

@@ -16,7 +16,7 @@
             <nav class="navigationbar">
                 <a href="index.html" class="nav-button">Main Page</a>
                 <a href="participate.html" class="nav-button">Participate</a>
-                <a href="schedule.html" class="nav-button">Schedule</a>
+                <a href="https://tdf3.schedule.cttue.de/tdf3/schedule/" class="nav-button">Schedule</a>
                 <a href="recap.html" class="nav-button inactive">Recap</a>
             </nav>
 
@@ -31,7 +31,7 @@
                 <p>On July 6, 2024, the 3rd Day of Digital Freedom took place in Tübingen's Westspitze. It was organized by
                     <a href="https://cttue.de/">Chaostreff Tübingen e.V.</a> Thanks to the support of many <a
                         href="participate.html">helping hands</a> and financial
-                    supporters, a fabulous event took place. Over 250 visitors were able to experience a <a href="schedule.html">diverse program</a>
+                    supporters, a fabulous event took place. Over 250 visitors were able to experience a <a href="https://tdf3.schedule.cttue.de/tdf3/schedule/">diverse program</a>
                     across four floors and six venues.</p>
             </div>