fix: downgrade nuget packages

Author: viceice

EPPlus/EPPlus.csproj

@@ -39,7 +39,22 @@
 
     <PackageReference Include="Microsoft.NETFramework.ReferenceAssemblies" Version="1.0.3" PrivateAssets="All" />
   </ItemGroup>
-  <ItemGroup Condition=" '$(TargetFramework)' != 'net462'">
+
+  <ItemGroup Condition=" '$(TargetFramework)' == 'netstandard2.0'">
+    <PackageReference Include="Microsoft.Extensions.Configuration.Json" Version="6.0.0" />
+    <PackageReference Include="System.ComponentModel.TypeConverter" Version="4.3.0" />
+    <PackageReference Include="System.Data.Common" Version="4.3.0" />
+    <PackageReference Include="System.Drawing.Common" Version="4.7.3" />
+    <PackageReference Include="System.Reflection" Version="4.3.0" />
+    <PackageReference Include="System.Security.Claims" Version="4.3.0" />
+    <PackageReference Include="System.Security.Cryptography.Pkcs" Version="6.0.1" />
+    <PackageReference Include="System.Security.Cryptography.X509Certificates" Version="4.3.2" />
+    <PackageReference Include="System.Text.Encoding.CodePages" Version="6.0.0" />
+    <PackageReference Include="System.Xml.XmlDocument" Version="4.3.0" />
+    <PackageReference Include="System.Xml.XPath.XmlDocument" Version="4.3.0" />
+  </ItemGroup>
+
+  <ItemGroup Condition=" '$(TargetFramework)' == 'net6.0'">
     <PackageReference Include="Microsoft.Extensions.Configuration.Json" Version="7.0.0" />
     <PackageReference Include="System.ComponentModel.TypeConverter" Version="4.3.0" />
     <PackageReference Include="System.Data.Common" Version="4.3.0" />