Update tables doesn't check for file existence

[ianepreston]

Probably other functions too. At least update_tables doesn't. Noticed it in the StatsCan class, but this should be fixed at the function level

[jasonrwang]

Hi @ianepreston, I've been handling this through simply excepting a FileNotFoundError but have also run into a couple of ConnectionErrors recently. I haven't been able to isolate if it's my VPN, ISP, StatCan's servers, or what.

Anyways, not sure if that's the best way to deal with this through the package but happy to try and make a PR using my implementation.