Bump Microsoft.VisualStudio.Threading in /dev-proxy

Bumps [Microsoft.VisualStudio.Threading](https://github.com/microsoft/vs-threading) from 17.11.20 to 17.12.19.
- [Release notes](https://github.com/microsoft/vs-threading/releases)
- [Commits](https://github.com/microsoft/vs-threading/commits)

---
updated-dependencies:
- dependency-name: Microsoft.VisualStudio.Threading
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

dev-proxy/dev-proxy.csproj

@@ -37,7 +37,7 @@
     <PackageReference Include="Microsoft.Extensions.Logging.Console" Version="8.0.1" />
     <PackageReference Include="Microsoft.IdentityModel.Protocols.OpenIdConnect" Version="8.1.2" />
     <PackageReference Include="Microsoft.OpenApi.Readers" Version="1.6.22" />
-    <PackageReference Include="Microsoft.VisualStudio.Threading" Version="17.11.20" />
+    <PackageReference Include="Microsoft.VisualStudio.Threading" Version="17.12.19" />
     <PackageReference Include="Newtonsoft.Json" Version="13.0.3" />
     <PackageReference Include="Swashbuckle.AspNetCore" Version="6.9.0" />
     <PackageReference Include="System.CommandLine" Version="2.0.0-beta4.22272.1" />