Upgrade to Java 21 EA build 21

Author: bclozel

ci/images/get-jdk-url.sh

@@ -9,7 +9,7 @@ case "$1" in
 		echo "https://github.com/bell-sw/Liberica/releases/download/20.0.1+10/bellsoft-jdk20.0.1+10-linux-amd64.tar.gz"
 	;;
   java21)
-    echo "https://download.java.net/java/early_access/jdk21/20/GPL/openjdk-21-ea+20_linux-x64_bin.tar.gz"
+    echo "https://download.java.net/java/early_access/jdk21/21/GPL/openjdk-21-ea+21_linux-x64_bin.tar.gz"
   ;;
 	*)
 		echo $"Unknown java version"