If you have released a work under GPL, that work stays under GPL. The term "relicensing" here means that going forward, new new works will be released under new licenses. So version 1 can be GPL, but version 2 can have other terms. We often don't think of new software releases to be independent works, but they kind of are.

Nothing can change the fact that version 1 was released under the terms of the GPL, but that does not mean you can use version 2 released under different terms.

Edit: this is assuming the maintainer is the primary author of the code. The current guidance from the FSF and other organizations that you need support from the authors of 95% of the work.