bump goa version used in design files (DSL)

Author: umbynos

design/design.go

@@ -15,7 +15,7 @@
 
 package design
 
-import . "goa.design/goa/dsl"
+import . "goa.design/goa/v3/dsl"
 
 var _ = API("arduino-create-agent", func() {
 	Title("Arduino Create Agent")

design/pkgs.go

@@ -15,7 +15,7 @@
 
 package design
 
-import . "goa.design/goa/dsl"
+import . "goa.design/goa/v3/dsl"
 
 var _ = Service("indexes", func() {
 	Description("The indexes service manages the package_index files")