Remove rust toolchain from shell.nix

For some reason rust-analyzer does not show clippy diagnostics when
installed this way.

Author: maxdexh

shell.nix

@@ -5,10 +5,7 @@ pkgs.mkShell {
   nativeBuildInputs = [ pkgs.pkg-config ];
 
   buildInputs = [
-    pkgs.cargo
-    pkgs.rustc
     pkgs.rustPlatform.bindgenHook
     pkgs.cairo
-    pkgs.rust-analyzer
   ];
 }