统一服务端c#语言版本为c#10

DotNet/Core/DotNet.Core.csproj

@@ -6,6 +6,7 @@
         <Nullable>disable</Nullable>
         <AssemblyName>Core</AssemblyName>
         <RootNamespace>ET</RootNamespace>
+        <LangVersion>10</LangVersion>
     </PropertyGroup>
 
     <PropertyGroup>

DotNet/ThirdParty/DotNet.ThirdParty.csproj

@@ -3,7 +3,7 @@
     <PropertyGroup>
         <TargetFramework>netstandard2.0</TargetFramework>
         <Nullable>disable</Nullable>
-        <LangVersion>9</LangVersion>
+        <LangVersion>10</LangVersion>
         <RootNamespace>ET</RootNamespace>
         <AssemblyName>ThirdParty</AssemblyName>
     </PropertyGroup>