Bump System.Buffers from 4.5.1 to 4.6.0

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] <support@github.com>

src/OpenSearch.Net/OpenSearch.Net.csproj

@@ -23,7 +23,7 @@
 
   <ItemGroup>
     <PackageReference Include="Microsoft.CSharp" Version="4.7.0" />
-    <PackageReference Include="System.Buffers" Version="4.5.1" />
+    <PackageReference Include="System.Buffers" Version="4.6.0" />
     <PackageReference Include="System.Diagnostics.DiagnosticSource" Version="8.0.1" />
 
     <PackageReference Condition="'$(TargetFramework)' == 'netstandard2.0'" Include="System.Reflection.Emit" Version="4.7.0" />