fix: Remove .NET Standard libraries from .NET Framework target (#2896)

Author: chynesNR

src/Agent/NewRelic/Agent/Core/Core.csproj

@@ -55,7 +55,9 @@
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
     </PackageReference>
     <PackageReference Include="Newtonsoft.Json" Version="13.0.3" />
-    <PackageReference Include="SharpZipLib" Version="1.4.2" />
+    <!-- 1.3.3 is the latest package of SharpZipLib that still has a .NET Framework target. Later versions
+    only have a .NET Standard target -->
+    <PackageReference Include="SharpZipLib" Version="1.3.3" />
     <PackageReference Include="System.Diagnostics.DiagnosticSource" Version="8.0.1" />
   </ItemGroup>