CSHARP-5266: Switch to Ubuntu for package creation (#1438)

Author: sanych-sun

evergreen/evergreen.yml

@@ -2705,7 +2705,7 @@ buildvariants:
 # Package release variants
 - matrix_name: build-packages
   matrix_spec:
-    os: "windows-64" # should produce package on Windows to build .NET framework (net472) packages.
+    os: "ubuntu-2004"
   display_name: "Packages Pack"
   tags: ["build-packages", "release-tag"]
   tasks:

src/Directory.Build.props

@@ -4,8 +4,7 @@
   </PropertyGroup>
 
   <PropertyGroup>
-    <TargetFrameworks>netstandard2.0;netstandard2.1</TargetFrameworks>
-    <TargetFrameworks Condition="'$(IsWindows)'=='true'">$(TargetFrameworks);net472</TargetFrameworks>
+    <TargetFrameworks>netstandard2.0;netstandard2.1;net472</TargetFrameworks>
     <LangVersion>10.0</LangVersion>
     <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
     <CodeAnalysisRuleSet>..\..\MongoDB.ruleset</CodeAnalysisRuleSet>
@@ -60,4 +59,4 @@
     <None Include="..\..\packageIcon.png" Pack="true" PackagePath="" />
     <None Include="..\..\README.md" Pack="true" PackagePath=""/>
   </ItemGroup>
-</Project>
+</Project>