ci: upgrade tsx and add node 20 back

[huozhi]

x-ref: https://github.com/huozhi/bunchee/actions/runs/6598833270/job/17927209278

error trace

console.error
      (node:2886) ExperimentalWarning: `--experimental-loader` may be removed in the future; instead use `register()`:
      --import 'data:text/javascript,import { register } from "node:module"; import { pathToFileURL } from "node:url"; register("file%3A///home/runner/work/bunchee/bunchee/node_modules/.pnpm/tsx%403.12.6/node_modules/tsx/dist/loader.js", pathToFileURL("./"));'
      (Use `node --trace-warnings ...` to show where the warning was created)

Old version of tsx doesn't support node 20 loader, upgrade tsx and add nodejs 20 back to CI