shell.nix: sync pkgs with unstable-channel

* new texlive
* obsoletes the required pkgs patch

shell.nix

@@ -3,32 +3,10 @@ let
   pkgsSrc = nixpkgs.pkgs.fetchFromGitHub {
     owner = "nixos";
     repo = "nixpkgs-channels";
-    rev = "6715afca34f7ece882b82c2250a4f6dade42eac5"; # vimtex update
+    rev = "2b0eace6cf021eed7123fb828483a00c95796829"; # vimtex update
-    sha256 = "1ix8k5sm01i75wxnfrlwbmc8xs8dn5zna7jb4v387h8zy8a74d8m";
+    sha256 = "187fmlkr4d1rbhrmcw8r3xnpxl22rvmisk1iswz3hj99j57ds5r6";
   };
-  pkgs = import (nixpkgs.stdenv.mkDerivation {
+  pkgs = import pkgsSrc {};
-    name = "patchedPackages";
-    src = pkgsSrc;
-
-    patches = [
-      (nixpkgs.fetchurl {
-        url="https://patch-diff.githubusercontent.com/raw/NixOS/nixpkgs/pull/15829.patch";
-        sha256 = "0a41nspiqs5i32pfzxqm8dp8qhfaajrw622lmlcvlvgbhpkac5r1";
-       })
-    ];
-
-    installPhase = ''
-      mkdir -p $out
-      cp -a * $out
-    '';
-
-    phases = ''
-      unpackPhase
-      patchPhase
-      installPhase
-    '';
-
-  }) {};
 
 in pkgs.stdenv.mkDerivation {
   name = "msc-thesis";