Add new version line: node 20.18.0

[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:node,type:node,version_filter:node-lts},version:{ref:20.18.0,url:https://nodejs.org/dist/v20.18.0/node-v20.18.0.tar.gz,sha256:c0819f8fc5038584d24c22002aeffd23f2d4a6fd6b337b30c502cbe4a659720c}}