refactor: remove types dependency

[ecrupper]

Follow up from go-vela/server#1213

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.30%. Comparing base (0d47b45) to head (8cdfc24).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #338   +/-   ##
=======================================
  Coverage   91.30%   91.30%           
=======================================
  Files          22       22           
  Lines        1634     1634           
=======================================
  Hits         1492     1492           
  Misses        106      106           
  Partials       36       36           

Files with missing lines	Coverage Δ
vela/admin.go	96.55% <100.00%> (ø)
vela/authentication.go	84.89% <100.00%> (ø)
vela/build.go	92.15% <100.00%> (ø)
vela/client.go	90.96% <100.00%> (ø)
vela/dashboard.go	100.00% <100.00%> (ø)
vela/deployment.go	91.89% <100.00%> (ø)
vela/hook.go	94.91% <100.00%> (ø)
vela/log.go	100.00% <100.00%> (ø)
vela/pipeline.go	77.61% <100.00%> (ø)
vela/queue.go	100.00% <100.00%> (ø)
... and 6 more

[KellyMerrick]

lgtm