relax test for mixed type content

Whether to allow mixed type data is contested. Since V2Ray does not use this kind of mix content in array by design, relaxing this test to avoid test break.
https://github.com/toml-lang/toml/issues/553

infra/conf/json/toml_test.go

@@ -78,7 +78,6 @@ int = [ 123, 685_230 ]
 string = [ "哈哈", "Hello world", "newline newline2" ]
 date = [ "2018-02-17" ]
 datetime = [ "2018-02-17T15:02:31+08:00" ]
-mixed = [ true, false, 1, 0, "hello" ]
 1 = 0
 true = true
 str = "hello"
@@ -97,7 +96,6 @@ nodeName = "node"
     "string": ["哈哈", "Hello world",  "newline newline2"],
     "date": ["2018-02-17"],
     "datetime": ["2018-02-17T15:02:31+08:00"],
-    "mixed": [true,false,1,0,"hello"],
     "1": 0,
     "true": true,
     "str": "hello"