Bump prometheus-net.AspNetCore from 7.0.0 to 8.0.0 in /src (#1774)

Bumps [prometheus-net.AspNetCore](https://github.com/prometheus-net/prometheus-net) from 7.0.0 to 8.0.0.
- [Release notes](https://github.com/prometheus-net/prometheus-net/releases)
- [Changelog](https://github.com/prometheus-net/prometheus-net/blob/master/History)
- [Commits](prometheus-net/prometheus-net@v7.0.0...v8.0.0)

---
updated-dependencies:
- dependency-name: prometheus-net.AspNetCore
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

src/AzureIoTHub.Portal.Server/AzureIoTHub.Portal.Server.csproj

@@ -68,7 +68,7 @@
     <PackageReference Include="MudBlazor" Version="6.1.9" />
     <PackageReference Include="NetEscapades.AspNetCore.SecurityHeaders" Version="0.18.0" />
     <PackageReference Include="Newtonsoft.Json" Version="13.0.2" />
-    <PackageReference Include="prometheus-net.AspNetCore" Version="7.0.0" />
+    <PackageReference Include="prometheus-net.AspNetCore" Version="8.0.0" />
     <PackageReference Include="Quartz" Version="3.6.0" />
     <PackageReference Include="Quartz.Extensions.Hosting" Version="3.6.0" />
     <PackageReference Include="Quartz.Serialization.Json" Version="3.6.0" />