build: deprecate zesty, add bionic PPA

build/ci.go

@@ -121,7 +121,8 @@ var (
 	// Note: vivid is unsupported because there is no golang-1.6 package for it.
 	// Note: wily is unsupported because it was officially deprecated on lanchpad.
 	// Note: yakkety is unsupported because it was officially deprecated on lanchpad.
-	debDistros = []string{"trusty", "xenial", "zesty", "artful"}
+	// Note: zesty is unsupported because it was officially deprecated on lanchpad.
+	debDistros = []string{"trusty", "xenial", "artful", "bionic"}
 )
 
 var GOBIN, _ = filepath.Abs(filepath.Join("build", "bin"))