ci: Add GitHub context dump step [skip ci]

.github/workflows/test-action.yml

@@ -32,6 +32,11 @@ jobs:
     steps:
       - uses: actions/checkout@v2
 
+      - name: Dump GitHub context
+        env:
+          GITHUB_CONTEXT: ${{ toJson(github) }}
+        run: echo "${GITHUB_CONTEXT}"
+
       - name: Read .nvmrc
         run: echo "::set-output name=NVMRC::$(cat .nvmrc)"
         id: nvm