Update dependency GitVersion.MsBuild to v6

Author: renovate[bot]

SIL.NuGetCleaner/SIL.NuGetCleaner.csproj

@@ -22,7 +22,7 @@ See full changelog at https://github.com/sillsdev/SIL.NuGetCleaner/blob/master/C
 
   <ItemGroup>
     <PackageReference Include="CommandLineParser" Version="2.9.1" />
-    <PackageReference Include="GitVersion.MsBuild" Version="5.12.0">
+    <PackageReference Include="GitVersion.MsBuild" Version="6.4.0">
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
     </PackageReference>