The PHP license doesn't place any constraints on what you do with stuff you build with it. If you want to GPL something you've produced with PHP, there's nothing in the PHP license stopping you.
Note also that even if there was, you could distribute the source form of your framework under the GPL just fine - the license on a particular piece of software does not extend to plain text that may or may not be used as input to the software.
IANAL, though.
