[actions] release.yml: provide GH_TOKEN so release-notes PR lookup can run

In GitHub Actions, `gh` refuses to run without a token,
and `release-notes.sh` fails closed on `gh` errors,
so the `make release` dry run died once the script was checked in.
The workflow already permits `api.github.com` egress and only needs the default read-only token.

Author: ljharb

.github/workflows/release.yml

@@ -35,5 +35,6 @@ jobs:
         run: echo proceed | make TAG=99.99.99 release
         env:
           GIT_EDITOR: "sed -i '1 s/^/99.99.99 make release test/'"
+          GH_TOKEN: ${{ github.token }}
       - name: Ensure tag is created
         run: git tag | grep v99.99.99