Move TycohConnectorTest project to Java 21

Effort to stabilize tests on MacOS.

Author: akurtakov

org.eclipse.m2e.pde.connector.tests/projects/tycho/pde.tycho.plugin.with.ds/META-INF/MANIFEST.MF

@@ -5,4 +5,4 @@ Bundle-Version: 0.0.1.qualifier
 Service-Component: OSGI-INF/pde.tycho.plugin.with.ds.AComponent.xml
 Automatic-Module-Name: pde.tycho.plugin.with.ds
 Bundle-ActivationPolicy: lazy
-Bundle-RequiredExecutionEnvironment: JavaSE-17
+Bundle-RequiredExecutionEnvironment: JavaSE-21