teamspeak6-client: fix update script, apply shellcheck

pkgs/by-name/te/teamspeak6-client/package.nix

@@ -114,7 +114,7 @@ stdenvNoCC.mkDerivation (finalAttrs: {
     runHook postInstall
   '';
 
-  updateScript = ./update.sh;
+  passthru.updateScript = ./update.sh;
 
   meta = {
     description = "TeamSpeak voice communication tool (beta version)";

pkgs/by-name/te/teamspeak6-client/update.sh

@@ -1,5 +1,5 @@
 #!/usr/bin/env nix-shell
-#!nix-shell --pure -i bash -p bash curl cacert ripgrep nix nix-update
+#!nix-shell --pure -i bash -p bash curl cacert ripgrep nix nix-update git
 set -euo pipefail
 
 latest_version=$(
@@ -18,4 +18,4 @@ if [[ "$latest_version" == "$current_version" ]]; then
     exit 0
 fi
 
-nix-update teamspeak6-client --version $latest_version
+nix-update teamspeak6-client --version "$latest_version"