Upgrade .NET SDK version to 9.0 in Dockerfile

Author: kevbite

Dockerfile

@@ -1,7 +1,7 @@
 ARG CONFIGURATION="Release"
 ARG NUGET_PACKAGE_VERSION="1.0.0"
 ARG COMPANIES_HOUSE_API_KEY
-FROM mcr.microsoft.com/dotnet/sdk:7.0 AS restore
+FROM mcr.microsoft.com/dotnet/sdk:9.0 AS restore
 
 ARG CONFIGURATION
 
@@ -44,4 +44,4 @@ COPY --from=pack /artifacts/*.snupkg /artifacts/
 COPY --from=test /tests/CompaniesHouse.Extensions.Microsoft.DependencyInjection.Tests/TestResults/*.trx /TestResults/CompaniesHouse.Extensions.Microsoft.DependencyInjection.Tests/
 COPY --from=test /tests/CompaniesHouse.IntegrationTests/TestResults/*.trx /TestResults/CompaniesHouse.IntegrationTests/
 COPY --from=test /tests/CompaniesHouse.ScenarioTests/TestResults/*.trx /TestResults/CompaniesHouse.ScenarioTests/
-COPY --from=test /tests/CompaniesHouse.Tests/TestResults/*.trx /TestResults/CompaniesHouse.Tests/
+COPY --from=test /tests/CompaniesHouse.Tests/TestResults/*.trx /TestResults/CompaniesHouse.Tests/