I was wondering if I could vote for my pizza ?

This should not only be allowed but strongly encouraged, despite looking not very honourable at first glance.
If all participants were to cast a vote on their own pizza, that would even things out and would effectively have no impact.
But if voting on their own pizza is disallowed or frowned upon, then it discourages participants from voting at all (i.e. on other pizzas) as that would be acting against their interest.
Maybe for the next edition, we could have a rule that you can vote on your own pizza, but only if you also cast votes on other ones.
But what's wrong with voting for your own pizza? I don't see anything wrong with that, nor do I see how it could influence the final vote. I'm comfortable saying that, because I didn't make any pizza.
A quick analysis, there are 144 pizzas (users), each user must vote on 5 pizzas. Even if the pizza creator votes on your pizza, he will still select 4 more different pizzas. Voting for your pizza won't make things that different in the final result. Voting for your pizza won't make things that different in the final result.
Furthermore, theoretically no one knows whose pizzas they are (I said theoretically). So, if a user votes for 5 pizzas, I can't tell if he voted for yours or not (theoretically speaking).
In short, I don't see a problem with everyone voting for their own pizza.