add rank_photos package

pkgs/rank_photos/default.nix

@@ -0,0 +1,33 @@
+{ stdenv, fetchFromGitLab, python3}:
+
+stdenv.mkDerivation {
+  name = "rank_photos";
+  version = "1.0.0";
+  
+  src = fetchFromGitLab {
+    domain = "git.dodsorf.as";
+    owner = "dandellion";
+    repo = "elo-rank-photos";
+    rev = "7db05f656515f89e837efdc2661363c131f3a6c0";
+    sha256 = "08fkv348vgivxpqrx36q7y0ax069i4ypp8ya46jnj8fnx40dzxzk";
+  };
+
+  buildInputs = [(python3.withPackages (pythonPackages: with pythonPackages; [
+    matplotlib
+    tkinter
+    numpy
+    exifread
+    pillow
+  ]))];
+
+  installPhase = ''
+    mkdir -p $out/bin
+    cp ./rank_photos.py $out/bin/rank_photos
+    chmod +x $out/bin/rank_photos
+  '';
+  
+  meta = {
+    description = "Compare and rank images by select which one is best and assigning elo ranking.";
+  };
+
+}