Fix concurrent map read/write race condition

Update deps

I hate doing this, but anacrolix/ffprobe has some nice fixes.

Remove public version const

Inspired by anacrolix#120 (comment).

Merge pull request anacrolix#97 from pataquets/add-docker-publish-ima…

…ge-action

Add Docker image publish Github action

Use go 1.16 in CI

goimports -w .