Downgrade eclipse.osgi to 3.18.0 (#4985)

This was updated to a wrong version in #4932.
Downgrade from 3.19.0 to 3.18.0 to sync with Karaf 4.4.8.

Signed-off-by: Holger Friedrich <mail@holger-friedrich.de>

Author: holgerfriedrich

features/karaf/openhab-tp/src/main/feature/feature.xml

@@ -260,7 +260,7 @@
 		<bundle dependency="true">mvn:org.eclipse.platform/org.eclipse.equinox.supplement/1.9.0</bundle>
 
 		<!-- Used for feature verification only because this is already provided by Karaf -->
-		<bundle dependency="true" start="false">mvn:org.eclipse.platform/org.eclipse.osgi/3.19.0</bundle>
+		<bundle dependency="true" start="false">mvn:org.eclipse.platform/org.eclipse.osgi/3.18.0</bundle>
 	</feature>
 
 	<feature name="openhab.tp-xtext-ide" description="Xtext - IDE Support" version="${project.version}">