Upgrade ecj to 3.21.0

Change-Id: Id337a320a59a77c36866f668ea1e30780bb55f35
Signed-off-by: David Pursehouse <david.pursehouse@gmail.com>
diff --git a/pom.xml b/pom.xml
index 6764644..070a1c5 100644
--- a/pom.xml
+++ b/pom.xml
@@ -895,7 +895,7 @@
               <dependency>
                 <groupId>org.eclipse.jdt</groupId>
                 <artifactId>ecj</artifactId>
-                <version>3.20.0</version>
+                <version>3.21.0</version>
               </dependency>
             </dependencies>
           </plugin>