Upgrade nexus to 3.53.1 or higher

[robe]

repo.osgeo.org is currently on 3.45.1

Latest available nexus is 3.53.1

there are no CVEE fixes noted, and most changes since seem to be aournd PostgreSQL as backend store (which we are not using, we are using the built-in database) and Ruby Gems. there is also a name change from Nexus Repository to Sonatype Nexus Repository.

One caution noted in the upgrades is possible issue with custom plugins.

"There is a known issue in Sonatype Nexus Repository 3.53.0 impacting those using community or custom plugins. These plugins will not load from the typical install directory and, in some cases, this may prevent Sonatype Nexus Repository from starting.

If you are using community or custom plugins and wish to upgrade, remove the plugin before doing so. Otherwise, wait to upgrade until we release a fix for this issue.

If you are not using community or custom plugins, there is no impact."

​https://help.sonatype.com/repomanager3/product-information/release-notes/2023-release-notes/sonatype-nexus-repository-3.53.0---3.53.1-release-notes

so I'll probably hold off for a bit longer till the next release comes out just in case.