Bump GitVersion.MsBuild from 6.7.0 to 6.8.1

---
updated-dependencies:
- dependency-name: GitVersion.MsBuild
  dependency-version: 6.8.1
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

src/Directory.Build.props

@@ -15,7 +15,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="GitVersion.MsBuild" Version="6.7.0" PrivateAssets="all" />
+    <PackageReference Include="GitVersion.MsBuild" Version="6.8.1" PrivateAssets="all" />
     <PackageReference Include="VCRuntime.CefSharp.140" Version="1.0.5" PrivateAssets="all" ExcludeAssets="build" />
   </ItemGroup>