telly v1.1.0-Beta7

updated go.mod, go.sum
Use standard crossbuild for docker build instead of spinning up a doc…
Support multicast streams through udpxy in the custom provider (#238)
ensure that ffmpeg processes are reaped to prevent zombies (#262)
Remove -re from ffmpeg command (#267)
Remove references to non-Custom providers.
Add a few more filetypes to ignore.
Issues #185, #265
Trimmed build platforms
tarballs require crossbuild
bump version