You can clone with
HTTPS or Subversion.
In short, just change your download URL in your packages.json to be on nodeload.github.com instead of just github.com.
The new version of package control uses HTTPS everywhere and checks certificates. This led someone to notice that your download URL for Format SQL is incorrect. While some downloaders on some platforms will redirect from github.com to nodeload.github.com, the github.com cert is not provided via package control because PC only explicitly uses nodeload.github.com, api.github.com and raw.github.com.
fixed & thank you, @wbond