Add linguist-generated=true for uv.lock (#26472)

## Summary & Motivation

Mark uv.lock as generated.

* Github doesn't render by default
* Graphite claims that it doesn't as well but that is not working right now. Asking in GraphiteSlack.
* Graphite Reviewer does not analyze

## How I Tested These Changes

![Screenshot 2024-12-13 at 9.51.50 AM.png](https://graphite-user-uploaded-assets-prod.s3.amazonaws.com/wS38mdcdU6aAeJobBdry/95a55b19-9a72-4f16-bcc5-c8f2eae88e34.png)

.gitattributes

@@ -1 +1,2 @@
-*.py diff=python
+*.py diff=python
+**/uv.lock linguist-generated