Conventional wisdom is that the most common places to find cofounders are at school or from working at other startups. I didn't study comp sci in school, so most of my tech connections came from my decision to leave the education sector for tech and the network I built in my time there. I've also met many tech people through local meetups.

I'll add that many people ITT are focusing on your "boring stuff" comment. I'm a founder, and honestly, the "business stuff" is not my favourite thing to do either; particularly sales. However, it also happens to be the most important work I do. Your comment indicates that it's not something you and your co-founders believe is valuable work. I hope that's not the case, but if it is you may struggle to engage a partner with this skillset.