ci: add dotnet pack and use Release

.github/workflows/build-debug.yaml

@@ -17,8 +17,9 @@ jobs:
     steps:
       - uses: Cysharp/Actions/.github/actions/checkout@main
       - uses: Cysharp/Actions/.github/actions/setup-dotnet@main
-      - run: dotnet build -c Debug
-      - run: dotnet test -c Debug
+      - run: dotnet build -c Release
+      - run: dotnet test -c Release
+      - run: dotnet pack -c Release --no-build -p:IncludeSymbols=true -o $GITHUB_WORKSPACE/artifacts
 
   build-unity:
     if: ${{ ((github.event_name == 'push' && github.repository_owner == 'Cysharp') || startsWith(github.event.pull_request.head.label, 'Cysharp:')) && github.triggering_actor != 'dependabot[bot]' }}

Directory.Build.props

@@ -1,8 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <Project ToolsVersion="15.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
   <PropertyGroup>
-    <LangVersion>13</LangVersion>
-
     <!-- NuGet Package Information -->
     <PackageVersion>$(Version)</PackageVersion>
     <Company>Cysharp</Company>