build: Target .NET 8 and .NET 9 (#8)

* build: Target .NET 8 and .NET 9
* fix: Remove TargetFramework specification for compatibility
* ci(codeql): Add .NET setup to CodeQL GitHub Actions workflow
* ci(codeql): Use manual build instead of autobuild

Author: hangy

.github/workflows/codeql.yml

@@ -46,8 +46,16 @@ jobs:
         with:
           languages: ${{ matrix.language }}
 
-      - name: Autobuild
-        uses: github/codeql-action/autobuild@v3
+      - name: Setup .NET
+        uses: actions/setup-dotnet@v4
+        with:
+          global-json-file: global.json
+          
+      - name: Restore dependencies
+        run: dotnet restore --locked-mode
+        
+      - name: Build
+        run: dotnet build --no-restore
 
       - name: Perform CodeQL Analysis
         uses: github/codeql-action/analyze@v3

Directory.Build.props

@@ -1,7 +1,7 @@
 <Project>
   <PropertyGroup>
     <LangVersion>preview</LangVersion>
-    <TargetFramework>net9.0</TargetFramework>
+    <TargetFrameworks>net8.0;net9.0</TargetFrameworks>
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
     <EnableNETAnalyzers>true</EnableNETAnalyzers>