bugfix: properly escape json, this is according to gh docs:

https://docs.github.com/en/actions/writing-workflows/choosing-what-your-workflow-does/accessing-contextual-information-about-workflow-runs#example-printing-context-information-to-the-log
actions/runner#1656

.github/workflows/ci.yml

@@ -36,7 +36,7 @@ jobs:
           RUNNER_CONTEXT: ${{ toJSON(runner) }}
         run: |
           mkdir contexts
-          echo '${{ toJSON(github) }}' | nix-shell -p jq --command "jq 'del(.token)' > contexts/github.json"
+          echo "$GITHUB_CONTEXT" | nix-shell -p jq --command "jq 'del(.token)' > contexts/github.json"
           echo "$RUNNER_CONTEXT" > contexts/runner.json
       - name: Upload context metadata as artifact
         uses: actions/upload-artifact@v4