Fix inconsistent test name

Co-authored-by: Crow Crowcrow <crow@fuyu.moe>
Co-committed-by: Crow Crowcrow <crow@fuyu.moe>

go.mod

@@ -0,0 +1,3 @@
+module git.fuyu.moe/Fuyu/validate
+
+go 1.17

rules_test.go

@@ -143,7 +143,7 @@ func TestRuleGteLte(t *testing.T) {
 	check(t, fail5, 1)
 }
 
-func TestLenMinMax(t *testing.T) {
+func TestRuleLenMinMax(t *testing.T) {
 	type s struct {
 		A string         `validate:"len=3"`
 		B []int          `validate:"min=2"`