s3proxy: skip tests on Darwin

Tests block forever on Darwin, but otherwise the package builds fine.

pkgs/by-name/s3/s3proxy/package.nix

@@ -1,4 +1,5 @@
 { lib
+, stdenv
 , fetchFromGitHub
 , jre
 , makeWrapper
@@ -20,6 +21,8 @@ maven.buildMavenPackage {
     hash = "sha256-GhZPvo8wlXInHwg8rSmpwMMkZVw5SMpnZyKqFUYLbrE=";
   };
 
+  mvnParameters = lib.optionalString stdenv.isDarwin "-DskipTests";
+
   nativeBuildInputs = [ makeWrapper ];
 
   installPhase = ''