youtrack: use jdk11 instead of jdk16

Youtrack supports jdk11 officially, with jdk16 it will initialize but
then fail with the error:

Unable to make protected final java.lang.Class java.lang.ClassLoader.defineClass(java.lang.String,byte[],int,int,java.security.ProtectionDomain) throws java.lang.ClassFormatError accessible: module java.base does not "opens java.lang" to unnamed module @26d27c7d

pkgs/servers/jetbrains/youtrack.nix

@@ -1,4 +1,4 @@
-{ lib, stdenv, fetchurl, makeWrapper, jre, gawk }:
+{ lib, stdenv, fetchurl, makeWrapper, jdk11, gawk }:
 
 stdenv.mkDerivation rec {
   pname = "youtrack";
@@ -15,10 +15,10 @@ stdenv.mkDerivation rec {
 
   installPhase = ''
     runHook preInstall
-    makeWrapper ${jre}/bin/java $out/bin/youtrack \
+    makeWrapper ${jdk11}/bin/java $out/bin/youtrack \
       --add-flags "\$YOUTRACK_JVM_OPTS -jar $jar" \
       --prefix PATH : "${lib.makeBinPath [ gawk ]}" \
-      --set JRE_HOME ${jre}
+      --set JRE_HOME ${jdk11}
     runHook postInstall
   '';