Bump dotnet/sdk from 8.0 to 9.0

Bumps dotnet/sdk from 8.0 to 9.0.

---
updated-dependencies:
- dependency-name: dotnet/sdk
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Dockerfile

@@ -5,7 +5,7 @@ WORKDIR /app
 EXPOSE 80
 EXPOSE 443
 
-FROM mcr.microsoft.com/dotnet/sdk:8.0 AS build
+FROM mcr.microsoft.com/dotnet/sdk:9.0 AS build
 WORKDIR /src
 COPY ["WoL.sln", "Directory.Build.props", "Directory.Packages.props", "./"]
 COPY ["WoL/WoL.csproj", "./WoL/"]