`drone-hugo` seems to be dead and you'll get errors about libresolv.so.2 when trying to use modern Hugo versions on it. This is due to incompatiblities between some versions of Alpine Linux and binaries build by Golang.You can make your own drone-hugo yourself, though:

snippet.yaml

- name: build
  image: "alpine:latest"
  commands:
    - apk add libc6-compat libstdc++ gcompat
    - apk add --no-cache --repository=https://dl-cdn.alpinelinux.org/alpine/edge/community hugo
    - hugo --config config.toml --contentDir content

This will always pull in the latest extended version of Hugo. If you wanted a specific version, you could combine a curl/wget command with a setting to grab and extract the specific release from GitHub.