update nixos to 20.03

nix/home.nix

@@ -35,8 +35,7 @@ in {
     jq
     keybase
     lastpass-cli
-    (let neuronSrc = builtins.fetchTarball https://github.com/srid/neuron/archive/master.tar.gz;
-  in import neuronSrc)
+    lorri
     nox
     tree
     ranger
@@ -46,9 +45,9 @@ in {
     zsh-history-substring-search
     zsh-syntax-highlighting
   ] ++ (if pkgs.stdenv.isDarwin then [
-    lorri
     skhd # keyboard shortcut daemon for macOS
   ] else [
+    calibre
     slack
   ]);