Flake: add nixpkgs patch

flake.nix

@@ -104,6 +104,7 @@
           name = "patched-nixpkgs-unstable";
           src = nixpkgs-unstable-raw;
           patches = [
+            ./nixpkgs-patches/revert-mangohud-update.patch
           ];
         };
         nixpkgs-patched = nixpkgs-raw.legacyPackages.x86_64-linux.applyPatches {

nixpkgs-patches/revert-mangohud-update.patch

@@ -0,0 +1,49 @@
+diff --git a/pkgs/tools/graphics/mangohud/default.nix b/pkgs/tools/graphics/mangohud/default.nix
+index cf83d4254baa..992afd60d3cb 100644
+--- a/pkgs/tools/graphics/mangohud/default.nix
++++ b/pkgs/tools/graphics/mangohud/default.nix
+@@ -24,8 +24,10 @@
+   unzip,
+   wayland,
+   libXNVCtrl,
++  nlohmann_json,
+   spdlog,
+   libxkbcommon,
++  glew,
+   glfw,
+   libXrandr,
+   x11Support ? true,
+@@ -93,14 +95,14 @@ let
+ in
+ stdenv.mkDerivation (finalAttrs: {
+   pname = "mangohud";
+-  version = "0.8.2";
++  version = "0.8.1";
+ 
+   src = fetchFromGitHub {
+     owner = "flightlessmango";
+     repo = "MangoHud";
+     tag = "v${finalAttrs.version}";
+     fetchSubmodules = true;
+-    hash = "sha256-BZ3R7D2zOlg69rx4y2FzzjpXuPOv913TOz9kSvRN+Wg=";
++    hash = "sha256-FvPhnOvcYE8vVB5R+ZRmuZxrC9U4GA338V7VAuUlHCE=";
+   };
+ 
+   outputs = [
+@@ -188,6 +190,7 @@ stdenv.mkDerivation (finalAttrs: {
+ 
+   buildInputs = [
+     dbus
++    nlohmann_json
+     spdlog
+   ]
+   ++ lib.optional waylandSupport wayland
+@@ -195,6 +198,7 @@ stdenv.mkDerivation (finalAttrs: {
+   ++ lib.optional nvidiaSupport libXNVCtrl
+   ++ lib.optional (x11Support || waylandSupport) libxkbcommon
+   ++ lib.optionals mangoappSupport [
++    glew
+     glfw
+     libXrandr
+   ];
+