webhook tag sha fix (#286)

[bkcsoft]

Fixes #286
Depends on go-gitea/go-sdk#21 (Don't merge before I've vendored it!)

Tag-hooks are pretty useless without specifying which shasum the new tag points at, this PR fixes that :)

Question: Should we also send the Shasum for "create branch"-events? (need to add another line in that case ^.^ ) Yes

[strk]

Why not ?
LGTM, but I guess you'll need to also add the vendor/ update once upstream is fixed (before merging this)

[bkcsoft]

@strk Not sure if we need it for new branches? and yes, need to vendor, but waiting for dep to be merged first :)

[lunny]

ci failed. and it seems your code is not the latest master.

[tboerger]

Just bump it with a comment when everything is done.

[bkcsoft]

@tboerger @lunny done :)

[tboerger]

LGTM