build: for now, specify java 8

Author: cmhulbert

pom.xml

@@ -106,6 +106,7 @@
 		<package-name>net.imglib2.type.label</package-name>
 		<license.licenseName>bsd_2</license.licenseName>
 		<license.copyrightOwners>Stephan Saalfeld</license.copyrightOwners>
+		<scijava.jvm.version>8</scijava.jvm.version>
 
 		<!-- NB: Deploy releases to the SciJava Maven repository. -->
 		<releaseProfiles>sign,deploy-to-scijava</releaseProfiles>