fix(ci): ignore .gradle files in license check (#17625)

The `check-license-header` script was failing with a `permission denied` error on `.gradle` files. This is because the `addlicense` tool was trying to process these files, which are build scripts and should not have license headers.

This commit fixes the issue by adding an ignore pattern for `.gradle` files to the `addlicense` command in both the `check-license-header` and `add-license-header` scripts in `melos.yaml`.

Co-authored-by: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>

Author: 2 people

melos.yaml

@@ -263,6 +263,7 @@ scripts:
     # "check-license-header".
     run: |
       addlicense -f header_template.txt \
+        --ignore "**/*.gradle" \
         --ignore "**/*.yml" \
         --ignore "**/*.yaml" \
         --ignore "**/*.xml" \
@@ -303,6 +304,7 @@ scripts:
     run: |
       addlicense -f header_template.txt \
         --check \
+        --ignore "**/*.gradle" \
         --ignore "**/*.yml" \
         --ignore "**/*.yaml" \
         --ignore "**/*.xml" \