⬆️ Bump xgboost from 1.6.1 to 1.6.2 in /testdata

Bumps [xgboost](https://github.com/dmlc/xgboost) from 1.6.1 to 1.6.2.
- [Release notes](https://github.com/dmlc/xgboost/releases)
- [Changelog](https://github.com/dmlc/xgboost/blob/master/NEWS.md)
- [Commits](https://github.com/dmlc/xgboost/commits)

---
updated-dependencies:
- dependency-name: xgboost
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

testdata/requirements.txt

@@ -1,4 +1,4 @@
-xgboost==1.6.1
+xgboost==1.6.2
 scikit-learn==1.1.2
 treelite==2.4.0
 treelite-runtime==2.4.0