Add contents: write permission to release workflow

[bdrhn9]

Problem

The release workflow failed during tag creation with the following error: https://github.com/api3dao/signed-api/actions/runs/20229930044/job/58070438146#step:10:29

Root Cause

The issue stems from the change in main.yml that removed token: ${{ secrets.GH_ACCESS_TOKEN }} from actions/checkout. This token is necessary because it works similarly to git clone https://${GH_USERNAME}:${GH_TOKEN}@github.com/api3dao/signed-api.git where Git saves the token credentials for subsequent operations.

Later in the workflow, we define GH_ACCESS_TOKEN in tag-and-release, but that's only used for Octokit actions within the createGithubRelease function. However, this function also executes native git push commands, which need the saved credentials. Without the token in actions/checkout, these git push operations fail.

Solution

Added contents: write permission to the tag-and-release job. This allows the default GITHUB_TOKEN to have write access, eliminating the need for the custom GH_ACCESS_TOKEN in the checkout step.

Testing

Confirmed the fix by testing all alternatives in a test repository: https://github.com/bdrhn9/test-release