Update dotnet.yml GitHub action to use net8.

Author: christophergunn

.github/workflows/dotnet.yml

@@ -16,7 +16,7 @@ jobs:
     - name: Setup .NET
       uses: actions/setup-dotnet@v1
       with:
-        dotnet-version: 5.0.x
+        dotnet-version: 8.0.x
     - name: Restore dependencies
       run: dotnet restore
     - name: Build

DockerComposeFixture.sln

@@ -7,6 +7,11 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "DockerComposeFixture", "Doc
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "DockerComposeFixture.Tests", "DockerComposeFixture.Tests\DockerComposeFixture.Tests.csproj", "{6FA8890B-5437-4135-B796-7A818CA5DBB6}"
 EndProject
+Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "build", "build", "{2CE05DD1-0760-44A3-AAD3-7A8D133B5244}"
+	ProjectSection(SolutionItems) = preProject
+		.github\workflows\dotnet.yml = .github\workflows\dotnet.yml
+	EndProjectSection
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU