format, add nixpkgs to xonsh

configuration.nix

@@ -169,7 +169,14 @@
     };
     firejail.enable = true;
     fish.enable = true;
-    xonsh.enable = true;
+    xonsh = {
+      enable = true;
+      package = pkgs.xonsh.overridePythonAttrs (
+        old: {
+          propagatedBuildInputs = old.propagatedBuildInputs ++ [ pkgs.python3Packages.nixpkgs ];
+        }
+      );
+    };
   };
 
   users = {

packages.nix

@@ -148,6 +148,7 @@ in
 
     # Development
     arduino
+    bear
     binutils-unwrapped
     ccache
     clang-tools
@@ -157,13 +158,16 @@ in
     gdb
     gnumake
     go
+    gopls
     jetbrains.clion
     llvm.clang
     llvm.lld
     nasm
+    nixpkgs-fmt
     nodejs
     patchelf
-    python37Packages.python-language-server
+    python3Packages.python-language-server
+    rnix-lsp
     rr
     rustup
     valgrind