Update go-buildkite to 4.19.0 (#777)

Author: matthewborden

go.mod

@@ -5,7 +5,7 @@ go 1.25.0
 require (
 	github.com/alecthomas/kong v1.15.0
 	github.com/anmitsu/go-shlex v0.0.0-20200514113438-38f4b401e2be
-	github.com/buildkite/go-buildkite/v4 v4.18.1-0.20260408232706-47eafe1749f2
+	github.com/buildkite/go-buildkite/v4 v4.19.0
 	github.com/buildkite/roko v1.4.0
 	github.com/buildkite/termoji v0.0.0-20260330080310-c0aa4ebee0d1
 	github.com/charmbracelet/bubbles v1.0.0

go.sum

@@ -33,8 +33,8 @@ github.com/bmatcuk/doublestar/v4 v4.6.1 h1:FH9SifrbvJhnlQpztAx++wlkk70QBf0iBWDwN
 github.com/bmatcuk/doublestar/v4 v4.6.1/go.mod h1:xBQ8jztBU6kakFMg+8WGxn0c6z1fTSPVIjEY1Wr7jzc=
 github.com/bradleyjkemp/cupaloy/v2 v2.6.0 h1:knToPYa2xtfg42U3I6punFEjaGFKWQRXJwj0JTv4mTs=
 github.com/bradleyjkemp/cupaloy/v2 v2.6.0/go.mod h1:bm7JXdkRd4BHJk9HpwqAI8BoAY1lps46Enkdqw6aRX0=
-github.com/buildkite/go-buildkite/v4 v4.18.1-0.20260408232706-47eafe1749f2 h1:NXO5ZhFPFGk2nD2H9m1+QqbGJqRs2LWlx4U+K0sSNp0=
-github.com/buildkite/go-buildkite/v4 v4.18.1-0.20260408232706-47eafe1749f2/go.mod h1:8+7GiWBKwEPAWoZnRU/kpNCt46j1iVH8kFMMbD4YDfc=
+github.com/buildkite/go-buildkite/v4 v4.19.0 h1:HPc6+V/Ky6v8eDWHxyvzHtxuhruCLUyuRrChOKvJE1I=
+github.com/buildkite/go-buildkite/v4 v4.19.0/go.mod h1:8+7GiWBKwEPAWoZnRU/kpNCt46j1iVH8kFMMbD4YDfc=
 github.com/buildkite/roko v1.4.0 h1:DxixoCdpNqxu4/1lXrXbfsKbJSd7r1qoxtef/TT2J80=
 github.com/buildkite/roko v1.4.0/go.mod h1:0vbODqUFEcVf4v2xVXRfZZRsqJVsCCHTG/TBRByGK4E=
 github.com/buildkite/termoji v0.0.0-20260330080310-c0aa4ebee0d1 h1:aaEl0QZURcwC+KOfFTzSp66xknw5eTmFZ1NgB87s2xk=