Use current Rodin update site instead of our Rodin 3.4 mirror

Can't use the corresponding current Eclipse update site yet, because of
some Tycho nonsense, but 2021-03 is still much better than Luna (2015).

build.gradle

@@ -2,9 +2,14 @@
 
 project.ext {
 	targetRepositories = [
-		"https://download.eclipse.org/releases/luna/",
+		// Temporarily using the Eclipse 2021-03 update site to stay compatible with Tycho < 2.1.0. See:
+		// https://bugs.eclipse.org/bugs/show_bug.cgi?id=564890#c16
+		// https://github.com/eclipse-tycho/tycho/commit/f4ec8f0c6c1e9fdecb096bbcfd4cd6c29cedf0d0
+		// Once we update Tycho (requires Java 11),
+		// this can be switched to Eclipse 2022-03 (same as Rodin 3.8 uses).
+		"https://download.eclipse.org/releases/2021-03/",
+		"https://rodin-b-sharp.sourceforge.net/core-updates/",
 		"https://rodin-b-sharp.sourceforge.net/updates",
-		"https://stups.hhu-hosting.de/buildlibs/org.rodinp.dev/",
 	]
 
 	groupID = "de.prob"

de.prob.core.tests/META-INF/MANIFEST.MF

@@ -6,7 +6,7 @@ Bundle-Version: 1.0.0.qualifier
 Bundle-Activator: de.prob.core.tests.Activator
 Require-Bundle: org.eclipse.ui,
  org.eclipse.core.resources,
- org.eclipse.core.runtime,
+ org.eclipse.core.runtime;bundle-version="[3.5.0,3.21.0)",
  org.eventb.core;bundle-version="[3.3.0,4.0.0)",
  org.eventb.core.ast;bundle-version="[3.3.0,4.0.0)",
  org.junit;bundle-version="[4.0.0,5.0.0)",