davmail: 6.4.0 -> 6.5.1

Currently using the Zulu JRE causes a runtime error where Davmail(/SWT?)
tries to access win32 libraries, and of course, it can't.

pkgs/by-name/da/davmail/package.nix

@@ -14,7 +14,7 @@
   gnugrep,
   zulu,
   preferGtk3 ? true,
-  preferZulu ? true,
+  preferZulu ? false,
 }:
 
 let
@@ -23,13 +23,13 @@ let
 in
 stdenv.mkDerivation (finalAttrs: {
   pname = "davmail";
-  version = "6.4.0";
+  version = "6.5.1";
 
   src = fetchFromGitHub {
     owner = "mguessan";
     repo = "davmail";
     tag = finalAttrs.version;
-    hash = "sha256-dj+7e0b8GcyoDzEWGG1SEMijqRBo1IJUFtgxkt9XNRU=";
+    hash = "sha256-D/MEWq696PFXlarQZdSrTS9VFODg7u7yhUsbCwHV9qs=";
   };
 
   buildPhase = ''