[Mirror] SSL error when pulling from GitHub

I try to create a mirrored repository and got this error

Error importing repository https://github.com/xxx/yyy.git into gperdomor/yyy - Cloning into bare repository '[REPOS PATH]/gperdomor/yyy.git'...
fatal: unable to access 'https://github.com/xxx/yyy.git/': SSL certificate problem: unable to get local issuer certificate