infra: license header check ignore target/ dir (#1954)

## Which issue does this PR close?


- Closes #.

## What changes are included in this PR?
Following the [release
verification](https://rust.iceberg.apache.org/release.html#how-to-verify-a-release)
step by step. The target/ dir gets picked up by license header check.

This PR adds the target/ dir to the ignore list.



## Are these changes tested?

Author: kevinjqliu

.licenserc.yaml

@@ -31,6 +31,7 @@ header:
     - "**/DEPENDENCIES.*.tsv"
     # Release distributions
     - "dist/*"
+    - "target"
     - "Cargo.lock"
     - "bindings/python/uv.lock"
     - ".github/PULL_REQUEST_TEMPLATE.md"