Handle correct exception when trying to call register_at_fork (rerun-…

…io#2685)

### What
Incorrect exception handling means we get an exception on windows.

### Checklist
* [x] I have read and agree to [Contributor
Guide](https://github.com/rerun-io/rerun/blob/main/CONTRIBUTING.md) and
the [Code of
Conduct](https://github.com/rerun-io/rerun/blob/main/CODE_OF_CONDUCT.md)
* [x] I've included a screenshot or gif (if applicable)
* [x] I have tested [demo.rerun.io](https://demo.rerun.io/pr/2685) (if
applicable)

- [PR Build Summary](https://build.rerun.io/pr/2685)
- [Docs
preview](https://rerun.io/preview/pr%3Ajleibs%2Fregister_at_fork_exception/docs)
- [Examples
preview](https://rerun.io/preview/pr%3Ajleibs%2Fregister_at_fork_exception/examples)

rerun_py/rerun_sdk/rerun/__init__.py

@@ -328,7 +328,7 @@ def _register_on_fork() -> None:
         import os
 
         os.register_at_fork(after_in_child=cleanup_if_forked_child)
-    except NotImplementedError:
+    except AttributeError:
         pass