nix: Fix the PATH of graphviz

Author: ibbem

default.nix

@@ -97,7 +97,7 @@ pkgs.stdenvNoCC.mkDerivation rec {
     local jar="$out/share/java/DiffDetective/DiffDetective.jar"
     install -Dm644 "target/diffdetective-${version}-jar-with-dependencies.jar" "$jar"
     makeWrapper "${pkgs.jdk}/bin/java" "$out/bin/DiffDetective" --add-flags "-cp \"$jar\"" \
-      --prefix PATH : "${pkgs.graphviz}"
+      --prefix PATH : "${pkgs.graphviz}/bin"
 
     ${
       if buildGitHubPages