Fix reference to e4.19 target to be e4.21

Change-Id: Ib1468472f36b22d88abdc525bc475675a185d2d7
Reviewed-on: https://git.eclipse.org/r/c/linuxtools/org.eclipse.linuxtools/+/183525
Tested-by: Linux Tools Bot <linuxtools-bot@eclipse.org>
Reviewed-by: Jeff Johnston <jjohnstn@redhat.com>

releng/org.eclipse.linuxtools.target/pom.xml

diff --git a/releng/org.eclipse.linuxtools.target/pom.xml b/releng/org.eclipse.linuxtools.target/pom.xml
index 6d02df6..4aaf415 100644
--- a/releng/org.eclipse.linuxtools.target/pom.xml
+++ b/releng/org.eclipse.linuxtools.target/pom.xml
@@ -31,9 +31,9 @@
               <configuration>
                 <artifacts>
                   <artifact>
-                    <file>linuxtools-e4.19.target</file>
+                    <file>linuxtools-e4.21.target</file>
                     <type>target</type>
-                    <classifier>linuxtools-e4.19</classifier>
+                    <classifier>linuxtools-e4.21</classifier>
                   </artifact>
                   <!-- More targets could be added here -->
                 </artifacts>