Update Microsoft.Extensions.Http.Polly requirement from 5.* to 7.*

Updates the requirements on [Microsoft.Extensions.Http.Polly](https://github.com/dotnet/aspnetcore) to permit the latest version.
- [Release notes](https://github.com/dotnet/aspnetcore/releases)
- [Changelog](https://github.com/dotnet/aspnetcore/blob/main/docs/ReleasePlanning.md)
- [Commits](https://github.com/dotnet/aspnetcore/commits)

---
updated-dependencies:
- dependency-name: Microsoft.Extensions.Http.Polly
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

src/Samples/Sample.AspNetCore/Sample.AspNetCore.csproj

@@ -14,7 +14,7 @@
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
     </PackageReference>
     <PackageReference Include="Microsoft.Extensions.Http" Version="6.*" />
-    <PackageReference Include="Microsoft.Extensions.Http.Polly" Version="6.*" />
+    <PackageReference Include="Microsoft.Extensions.Http.Polly" Version="7.*" />
     <PackageReference Include="Microsoft.Extensions.Logging.Abstractions" Version="6.*" />
     <PackageReference Include="Microsoft.Extensions.Logging.Debug" Version="6.*" />   
   </ItemGroup>