Bumped golang version to 1.21 in go.mod

Add AV1 codec id (#146)

* Add AV1 codec id

* sort codec_id alphabetically

Updated frame/packet side data Get() signature

Refactored frame/packet side data + added regions of interest to fram…

…e side data

SetMetadata method for Stream (#136)

* SetMetadata method for Stream

* add tests, change url in doc

Oopsie poopsie

Now using av_malloc/av_free instead of malloc/free

Fixed heap-use-after-free

Removed AllocImage and AllocSamples

Frame.Copy(dst *Frame) (#127)