Remove unnecessary dependencies (#3853)

Author: teo-tsirpanis

generator/ServiceClientGeneratorLib/ServiceClientGeneratorLib.csproj

@@ -735,9 +735,12 @@
       <LastGenOutput>AmazonS3RetryPolicy.cs</LastGenOutput>
     </None>
   </ItemGroup>
-  <ItemGroup>
+  <ItemGroup Condition="'$(TargetFramework)' == 'netstandard2.0'">
 	<PackageReference Include="Microsoft.CSharp" Version="4.4.1" />
   </ItemGroup>
+  <ItemGroup Condition="'$(TargetFramework)' == 'net45'">
+	<Reference Include="Microsoft.CSharp" />
+  </ItemGroup>
   <ItemGroup Condition="'$(TargetFramework)' != 'net45'">
 	<PackageReference Include="System.CodeDom" Version="6.0.0" />
   </ItemGroup>

sdk/test/NetStandard/UnitTests/AWSSDK.UnitTests.Custom.NetStandard.csproj

@@ -56,7 +56,6 @@ This project file should not be used as part of a release pipeline.
 
 	<ItemGroup>
 		<PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.7.2" />
-		<PackageReference Include="System.Text.RegularExpressions" Version="4.3.1" />
 		<PackageReference Include="xunit" Version="2.4.2" />
 		<PackageReference Include="Moq" Version="4.18.4" />
 		<PackageReference Include="xunit.runner.visualstudio" Version="2.4.5">