ci: Only use helm kubeval if installed

Author: nhooyr

ci/dev/lint.sh

@@ -8,7 +8,9 @@ main() {
   stylelint $(git ls-files "*.css")
   tsc --noEmit
   shellcheck -e SC2046,SC2164,SC2154,SC1091,SC1090,SC2002 $(git ls-files "*.sh")
-  helm kubeval ci/helm-chart
+  if command -v helm && helm kubeval --help > /dev/null; then
+    helm kubeval ci/helm-chart
+  fi
 }
 
 main "$@"