chore: target .NET 8 LTS in action and analyzer

.NET 7 has been out of support since May 2024. Bumps:
- TargetFramework net7.0 → net8.0
- actions/checkout v3 → v4
- actions/setup-dotnet v3 → v4

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: TheSmallPixel

action.yml

@@ -30,14 +30,14 @@ runs:
   using: "composite"
   steps:
     - name: Check out code
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
       with:
         persist-credentials: true
 
     - name: Set up .NET
-      uses: actions/setup-dotnet@v3
+      uses: actions/setup-dotnet@v4
       with:
-        dotnet-version: "7.0.x"
+        dotnet-version: "8.0.x"
 
     - name: Build Roslyn tool
       run: dotnet build --configuration Release ./tools/CodeAnalysisTool/CodeAnalysisTool.csproj

tools/CodeAnalysisTool/CodeAnalysisTool.csproj

@@ -1,8 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <!-- Change this to whatever .NET version you want, e.g. net6.0, net7.0, etc. -->
-    <TargetFramework>net7.0</TargetFramework>
+    <TargetFramework>net8.0</TargetFramework>
   </PropertyGroup>
 
   <ItemGroup>