Let the deploy job read the repository

The deploy action is referenced with $/, which the runner downloads from
this private repository at the running commit using the job's
GITHUB_TOKEN. Giving the job only actions: write left it without
contents: read, so setting up the job failed with "An action could not
be found".

Author: mudge

.github/workflows/build-and-deploy.yml

@@ -69,6 +69,7 @@ jobs:
     runs-on: ubuntu-latest
     permissions:
       actions: write
+      contents: read
     environment:
       name: ${{ inputs.environment }}
       url: ${{ inputs.url }}