Add new version line: bundler 4.0.3

[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:4.0.3,sha256:f06623d5edf4183e5fac847a953c1f1bd95e27aa766471525d3a9c70bdee9394,url:https://github.com/ruby/rubygems/tree/master/bundlertree/v4.0.3}}