Predictive back: enable.

Part of #1708.

src/main/AndroidManifest.xml

@@ -69,6 +69,7 @@ limitations under the License.
         android:allowBackup="true"
         android:fullBackupContent="@xml/backup_rules_30_lower"
         android:dataExtractionRules="@xml/backup_rules_31_higher"
+        android:enableOnBackInvokedCallback="true"
         android:hardwareAccelerated="true"
         android:hasFragileUserData="false"
         android:icon="@drawable/ic_launcher"

src/main/java/de/dennisguse/opentracks/AbstractActivity.java

@@ -40,7 +40,7 @@ public abstract class AbstractActivity extends AppCompatActivity {
 
     @Override
     public boolean onSupportNavigateUp() {
-        onBackPressed();
+        getOnBackPressedDispatcher().onBackPressed();
         return true;
     }