Fix printing of standards in prompt mode

The options were formatted as an array literal instead of just the
values delimited by a slash.

Author: friendlyanon

cmake-init/cmake_init.py

@@ -139,7 +139,7 @@ def ask(*args, **kwargs):
 library."""
         ),
         "std": ask(
-            f"{lang} standard ({lang.options})",
+            "{} standard ({})".format(lang, "/".join(lang.options)),
             cli_args.std or lang.default,
             predicate=lambda v: v in lang.options,
             header=f"{lang} standard to use. Defaults to {lang.default}.",