Bump Microsoft.OpenApi.Readers in /m365-developer-proxy (#355)

Bumps [Microsoft.OpenApi.Readers](https://github.com/Microsoft/OpenAPI.NET) from 1.6.8 to 1.6.9.
- [Release notes](https://github.com/Microsoft/OpenAPI.NET/releases)
- [Commits](microsoft/OpenAPI.NET@1.6.8...1.6.9)

---
updated-dependencies:
- dependency-name: Microsoft.OpenApi.Readers
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

m365-developer-proxy/m365-developer-proxy.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
@@ -32,7 +32,7 @@
     <PackageReference Include="Microsoft.Extensions.Configuration" Version="7.0.0" />
     <PackageReference Include="Microsoft.Extensions.Configuration.Binder" Version="7.0.4" />
     <PackageReference Include="Microsoft.Extensions.Configuration.Json" Version="7.0.0" />
-    <PackageReference Include="Microsoft.OpenApi.Readers" Version="1.6.8" />
+    <PackageReference Include="Microsoft.OpenApi.Readers" Version="1.6.9" />
     <PackageReference Include="System.CommandLine" Version="2.0.0-beta4.22272.1" />
     <PackageReference Include="Titanium.Web.Proxy" Version="3.2.0" />
   </ItemGroup>