tl2cgen and treelite version issue

Treelite 4.6.1 and tl2cgen 1.0.0 are installed in the project, and the `tl2cgen.export_lib` call would generate the following messages:

```
/tmp/tmpfk5q71dd/libbuild/_deps/treelite-src/src/serializer.cc:202: The model you are loading originated from a newer Treelite version; some functionalities may be unavailable.
Currently running Treelite version 4.1.2
The model checkpoint was generated from Treelite version 4.6.1
```

So far, the code still works. but in the long run, how the version mismatch would be handled?