Update go version in go.mod (go1.16).

_examples/go.mod

@@ -1,6 +1,6 @@
 module github.com/cucumber/godog/_examples
 
-go 1.16
+go 1.17
 
 replace github.com/cucumber/godog => ../
 
@@ -13,6 +13,15 @@ require (
 )
 
 require (
+	github.com/cucumber/gherkin-go/v19 v19.0.3 // indirect
+	github.com/cucumber/messages-go/v16 v16.0.1 // indirect
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/gofrs/uuid v4.2.0+incompatible // indirect
+	github.com/hashicorp/go-immutable-radix v1.3.1 // indirect
+	github.com/hashicorp/go-memdb v1.3.2 // indirect
+	github.com/hashicorp/golang-lru v0.5.4 // indirect
 	github.com/kr/pretty v0.3.0 // indirect
 	github.com/lib/pq v1.10.3 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b // indirect
 )