What should I do ?
No, IRCC will not decline your visa because of this. If you are eligible for the study visa it will be issued, you simply need to renew your passport when it is due for renewal and then apply for a visa extension if you need one. One of my former workmates in Canada was eligible for a 3 year post graduation work permit, but her passport only had 1 year to expiry. Immigration granted her a 1 year PGWP and asked her to return later with her new passport to get an extension. When she renewed her passport, she went back to immigration and got PGWP extended by another 2 years. Canada will not issue you a visa that extends beyond the expiry of your passport.