Patch cj end to upload a file instead of paste service

[D0rs4n]

• Due to changes in the interface of the Paste Service, for the duration of the code jam, the bot will send a text file.

[ChrisLovering]

A better approach would be to bump bot core to 10.X and use the util from there [...]

Since I wanted to update bot-core anyway, I've done this change in https://github.com/python-discord/sir-robin/pull/91

[ChrisLovering]

superseded by https://github.com/python-discord/sir-robin/pull/91