update workflow configs

Author: Zechiax

.github/workflows/dotnet.yml

@@ -13,7 +13,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        dotnet: [ '6.0.x', '8.0.x' ]
+        dotnet: [ '8.0.x' ]
     steps:
     - uses: actions/checkout@v4
     - name: Setup .NET

.github/workflows/publish.yml

@@ -13,7 +13,7 @@ jobs:
       - name: Setup dotnet
         uses: actions/setup-dotnet@v4
         with:
-          dotnet-version: '6.0.x'
+          dotnet-version: '8.0.x'
 
       # Publish
       - name: publish on version change

.github/workflows/static.yml

@@ -36,7 +36,7 @@ jobs:
       - name: Dotnet Setup
         uses: actions/setup-dotnet@v4
         with:
-          dotnet-version: '6.x'
+          dotnet-version: '8.x'
       - run: dotnet tool update -g docfx
       - run: dotnet build
       - run: docfx docfx.json