Fix request method

Author: mosaxiv

website/content/guide/testing.md

@@ -146,7 +146,7 @@ c.SetParamValues("1", "[email protected]")
 ```go
 q := make(url.Values)
 q.Set("email", "[email protected]")
-req := httptest.NewRequest(http.MethodPost, "/?"+q.Encode(), nil)
+req := httptest.NewRequest(http.MethodGet, "/?"+q.Encode(), nil)
 ```
 
 ## Testing Middleware