fix: only allow lowercase chars for new runtimes

tools/kystrap/cmd/create.go

@@ -14,7 +14,7 @@ import (
 	"github.com/spf13/cobra"
 )
 
-var regexpAlphaNumericAndDash = regexp.MustCompile(`^[a-zA-Z0-9-]+$`)
+var regexpAlphaNumericAndDash = regexp.MustCompile(`^[a-z0-9-]+$`)
 
 var (
 	flagLanguage = commoncmd.OptionFlag[types.Language]{
@@ -46,7 +46,7 @@ var (
 				return errors.New("name must be at least 3 characters long")
 			}
 			if !regexpAlphaNumericAndDash.MatchString(input) {
-				return errors.New("name must only contain alphanumeric characters and dashes")
+				return errors.New("name must only contain lowercase alphanumeric characters and dashes")
 			}
 			return nil
 		},