fix

Author: sungam3r

test/Serilog.Settings.Configuration.Tests/Support/Extensions.cs

@@ -13,7 +13,7 @@ public static object LiteralValue(this LogEventPropertyValue @this)
         // Could not parse the JSON file. System.Text.Json.JsonReaderException : ''' is an invalid start of a property name. Expected a '"'
         public static string ToValidJson(this string str)
         {
-#if NETCOREAPP3_0
+#if NETCOREAPP3_1
             str = str.Replace('\'', '"');
 #endif
             return str;