remove version tag from wit definitions (#1088)

It failed the [recent version
update](https://github.com/NomicFoundation/slang/actions/runs/10561509832/job/29257403873).
Let's remove it for now, as it is not used anywhere, and will only be
consumed in a later PR under the NPM package.

crates/codegen/runtime/cargo/src/runtime/wit/interface/_world.wit.jinja2

@@ -1,4 +1,4 @@
-package nomic-foundation:slang@{{ model.slang_version }};
+package nomic-foundation:slang;
 
 world slang {
     export cst;