allow header and footer to be passed as input

[jetersen]

Add header and footer via action. Which allows for GitHub template variables.

    steps:
      - name: Release Drafter
        uses: release-drafter/release-drafter@v5
        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
        with:
          header: "Hello"
          footer: "World"

Inside the header you could use GitHub template variables header like: Hello ${{ inputs.name }}