How to get access to my plugin?

As you can see here →

The github repo is under my name on that page GitHub - deanhiller/webpieces: A project containing all the web pieces (WITH apis) to create a web server (and an actual web server)

yet, I can’t seem to get access to it to upgrade the plugin.

The Gradle Plugin Portal doesn’t support multiple owners. Since one of your contributor’s published it with a personal account, it belongs to that account, not yours.

If you don’t want it to be a personal account, you can always create an account that represents your “organization” (even if it’s not really an organization by other definitions).

Either way, you’ll need to request a transfer if you don’t want to it to stay with the current account. You will have to share the credentials for whatever account that is if you want multiple people to publish locally, but ideally you have a CI/CD for the release process and the right people can trigger that automation without sharing the real credentials.