Bump StackExchange.Redis from 2.7.33 to 2.8.16 in /Difficalcy

Bumps [StackExchange.Redis](https://github.com/StackExchange/StackExchange.Redis) from 2.7.33 to 2.8.16.
- [Release notes](https://github.com/StackExchange/StackExchange.Redis/releases)
- [Changelog](https://github.com/StackExchange/StackExchange.Redis/blob/main/docs/ReleaseNotes.md)
- [Commits](StackExchange/StackExchange.Redis@2.7.33...2.8.16)

---
updated-dependencies:
- dependency-name: StackExchange.Redis
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Difficalcy/Difficalcy.csproj

@@ -10,7 +10,7 @@
 
   <ItemGroup>
     <PackageReference Include="Swashbuckle.AspNetCore" Version="6.6.2" />
-    <PackageReference Include="StackExchange.Redis" Version="2.7.33" />
+    <PackageReference Include="StackExchange.Redis" Version="2.8.16" />
   </ItemGroup>
 
 </Project>