Add new version line: bundler 4.0.0

[cf-buildpacks-eng]

Please edit the dependency-builds pipeline to add the new version line to the relevant dependency/buildpack.

For nginx/nginx-static: Also remove older mainline/stable version.
E.g. If you are adding nginx 1.22, you will remove 1.20. If you are adding 1.23, you will remove 1.21

{source:{name:bundler,type:rubygems},version:{ref:4.0.0,sha256:7d9461e65e813863ce9b710d5b2f3636d1b4904ea64595e54e957a25d721bd3d,url:https://github.com/ruby/rubygems/tree/master/bundlertree/v4.0.0}}