feat(release): add publish only flag

[dawidvdh]

Hi, I have attempted to add an argument in order to be able to only publish and not create git tags and github releases, I don't have too much context over this project so I very well may be missing something please do let me know and I will try fix it.

However I am trying to achieve this as I am currently in a situation where I need to publish to both the npm registry and the github package registry, I am currently achieving it by doing the following:

      - uses: actions/setup-node@v3
        with:
          node-version-file: ".nvmrc"
          registry-url: "https://registry.npmjs.org"
      - run: npm install
      - run: npx shipjs trigger
        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
          NPM_AUTH_TOKEN: ${{ secrets.NPM_AUTH_TOKEN }}
          SLACK_INCOMING_HOOK: ${{ secrets.SLACK_INCOMING_HOOK }}
      - uses: actions/setup-node@v3
        with:
          node-version-file: ".nvmrc"
          registry-url: "https://npm.pkg.github.com"
      - run: npx shipjs trigger -- --publishOnly
        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
          NPM_AUTH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
          NODE_AUTH_TOKEN: ${{ secrets.GITHUB_TOKEN }}

I set publishOnly in hopes that it would only push the package up to the github registry, however it still attempts to recreate the tag and of course fails:

npm notice Publishing to https://npm.pkg.github.com/
+ @project/package@1.0.0
› Creating a git tag.
$ git tag v1.0.2
fatal: tag 'v1.0.2' already exists
Error: {
  "message": "Exit code is 128",
  "command": "git tag v1.0.2",
  "result": ""
}
    at exec (/home/runner/work/project/node_modules/shipjs-lib/dist/index.esm.js:44:11)
    at default (/home/runner/work/project/node_modules/shipjs/src/util/run.js:22:20)
    at /home/runner/work/project/node_modules/shipjs/src/step/release/createGitTag.js:9:5
    at runStep (/home/runner/work/project/node_modules/shipjs/src/step/runStep.js:11:10)
    at default (/home/runner/work/project/node_modules/shipjs/src/step/release/createGitTag.js:5:3)
    at release (/home/runner/work/project/node_modules/shipjs/src/flow/release.js:45:23)
    at async Proxy.cli (/home/runner/work/project/node_modules/shipjs/src/cli.js:48:5)
    at async /home/runner/work/project/node_modules/shipjs/bin/shipjs:7:5
Error: Process completed with exit code 1.

If there is a better solution to achieve this please do let me know.

[Haroenv]

Thanks for your PR! Before setting this new option, could you pass publishCommand that would publish to both npm and GitHub registry, so you only need to trigger once?