Bump System.Buffers from 4.5.1 to 4.6.0 (#183)

Bumps [System.Buffers](https://github.com/dotnet/maintenance-packages) from 4.5.1 to 4.6.0.
- [Release notes](https://github.com/dotnet/maintenance-packages/releases)
- [Commits](https://github.com/dotnet/maintenance-packages/commits)

---
updated-dependencies:
- dependency-name: System.Buffers
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

src/Directory.Packages.props

@@ -19,7 +19,7 @@
     <PackageVersion Include="Microsoft.NET.Test.SDK" Version="17.11.1" />
     <PackageVersion Include="Mono.Options" Version="6.12.0.148" />
     <PackageVersion Include="MSBuild.StructuredLogger" Version="2.2.243" />
-    <PackageVersion Include="System.Buffers" Version="4.5.1" />
+    <PackageVersion Include="System.Buffers" Version="4.6.0" />
     <PackageVersion Include="System.IO.Compression" Version="4.3.0" />
     <PackageVersion Include="xunit" Version="2.9.2" />
     <PackageVersion Include="xunit.runner.visualstudio" Version="2.8.2" />