Update vendor dependencies

vendor/github.com/gorilla/mux/mux_test.go

@@ -2248,6 +2248,15 @@ func TestMethodsSubrouterPathVariable(t *testing.T) {
 	}
 }
 
+func ExampleSetURLVars() {
+	req, _ := http.NewRequest("GET", "/foo", nil)
+	req = SetURLVars(req, map[string]string{"foo": "bar"})
+
+	fmt.Println(Vars(req)["foo"])
+
+	// Output: bar
+}
+
 // testMethodsSubrouter runs an individual methodsSubrouterTest.
 func testMethodsSubrouter(t *testing.T, test methodsSubrouterTest) {
 	// Execute request
@@ -2306,6 +2315,14 @@ func stringMapEqual(m1, m2 map[string]string) bool {
 	return true
 }
 
+// stringHandler returns a handler func that writes a message 's' to the
+// http.ResponseWriter.
+func stringHandler(s string) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		w.Write([]byte(s))
+	}
+}
+
 // newRequest is a helper function to create a new request with a method and url.
 // The request returned is a 'server' request as opposed to a 'client' one through
 // simulated write onto the wire and read off of the wire.