Capture specific exception types in `except`

[JPTIZ]

Some exception handling code take the generic type Exception in except and, in a couple cases:

pico-bot/picobot/handlers.py

Line 175 in f4c6255

if isinstance(exc, telegram.error.BadRequest):

pico-bot/picobot/handlers.py

Line 220 in f4c6255

if isinstance(exc, telegram.error.BadRequest):

pico-bot/picobot/handlers.py

Line 272 in f4c6255

if isinstance(exc, telegram.error.BadRequest):

And, after #34 is merged:

pico-bot/picobot/handlers.py

Line 342 in 033e461

if isinstance(exc, VideoTooLongError):

So instead of doing:

except Exception as exc:
    if isinstance(exc, SpecificType):

We should slightly rework the code to get exceptions as:

except SpecificType as error: