ci(lint): enable usestdlibvars linter (#4091)

Signed-off-by: Matthieu MOREL <matthieu.morel35@gmail.com>

utils_test.go

@@ -29,7 +29,7 @@ type testStruct struct {
 }
 
 func (t *testStruct) ServeHTTP(w http.ResponseWriter, req *http.Request) {
-	assert.Equal(t.T, "POST", req.Method)
+	assert.Equal(t.T, http.MethodPost, req.Method)
 	assert.Equal(t.T, "/path", req.URL.Path)
 	w.WriteHeader(http.StatusInternalServerError)
 	fmt.Fprint(w, "hello")
@@ -39,17 +39,17 @@ func TestWrap(t *testing.T) {
 	router := New()
 	router.POST("/path", WrapH(&testStruct{t}))
 	router.GET("/path2", WrapF(func(w http.ResponseWriter, req *http.Request) {
-		assert.Equal(t, "GET", req.Method)
+		assert.Equal(t, http.MethodGet, req.Method)
 		assert.Equal(t, "/path2", req.URL.Path)
 		w.WriteHeader(http.StatusBadRequest)
 		fmt.Fprint(w, "hola!")
 	}))
 
-	w := PerformRequest(router, "POST", "/path")
+	w := PerformRequest(router, http.MethodPost, "/path")
 	assert.Equal(t, http.StatusInternalServerError, w.Code)
 	assert.Equal(t, "hello", w.Body.String())
 
-	w = PerformRequest(router, "GET", "/path2")
+	w = PerformRequest(router, http.MethodGet, "/path2")
 	assert.Equal(t, http.StatusBadRequest, w.Code)
 	assert.Equal(t, "hola!", w.Body.String())
 }
@@ -119,13 +119,13 @@ func TestBindMiddleware(t *testing.T) {
 		called = true
 		value = c.MustGet(BindKey).(*bindTestStruct)
 	})
-	PerformRequest(router, "GET", "/?foo=hola&bar=10")
+	PerformRequest(router, http.MethodGet, "/?foo=hola&bar=10")
 	assert.True(t, called)
 	assert.Equal(t, "hola", value.Foo)
 	assert.Equal(t, 10, value.Bar)
 
 	called = false
-	PerformRequest(router, "GET", "/?foo=hola&bar=1")
+	PerformRequest(router, http.MethodGet, "/?foo=hola&bar=1")
 	assert.False(t, called)
 
 	assert.Panics(t, func() {