Update deprecation message

[DerekTBrown]

The following code triggers a CLANGTIDY lint:

return ranges::views::empty<int64_t>();

is deprecated Replace views::empty() with views::empty<>. It is now a variable template.

If I do as the lint suggests, I get a template error:

return ranges::views::empty<>;

error: too few template arguments for variable template 'empty'

I suspect we actually want the lint message to be:

is deprecated Replace views::empty() with views::empty<T>. It is now a variable template.

[ericniebler]

Thanks!