ci: Update GitHub Actions workflow

- Changed the workflow name from ".NET Core" to ".NET Core - Build and Test".
- Updated `actions/checkout` action from version 2 to version 4.
- Updated `actions/setup-dotnet` action from version 1 to version 4.
- Commented out the `Publish` step, which included adding a NuGet source, packing projects, and pushing the packages to GitHub and NuGet.

.github/workflows/dotnet-core.yml

@@ -1,4 +1,4 @@
-name: .NET Core
+name: .NET Core - Build and Test
 
 on: [push, pull_request]
 
@@ -8,8 +8,8 @@ jobs:
     runs-on: windows-latest
 
     steps:
-    - uses: actions/checkout@v2 
-    - uses: actions/setup-dotnet@v1
+    - uses: actions/checkout@v4
+    - uses: actions/setup-dotnet@v4
       with:
         dotnet-version: '9.x'
         include-prerelease: true
@@ -23,11 +23,11 @@ jobs:
         dotnet build Demos --configuration Release --no-restore
     - name: Test
       run: dotnet test DemoTests -c Release --verbosity normal
-    - name: Publish
-      if: github.event_name != 'pull_request'
-      run: |
-        dotnet nuget add source "https://nuget.pkg.github.com/bepu/index.json" --name "github" --username "rossnordby" --password "${{secrets.GITHUB_TOKEN}}"
-        dotnet pack "BepuPhysics" -c Release
-        dotnet pack "BepuUtilities" -c Release
-        dotnet nuget push "**/*.nupkg" -s "github" -k "${{secrets.GITHUB_TOKEN}}" --skip-duplicate
-        dotnet nuget push "**/*.nupkg" -s "https://api.nuget.org/v3/index.json" -k "${{secrets.NUGET_KEY}}" --skip-duplicate
+#    - name: Publish
+#      if: github.event_name != 'pull_request'
+#      run: |
+#        dotnet nuget add source "https://nuget.pkg.github.com/bepu/index.json" --name "github" --username "rossnordby" --password "${{secrets.GITHUB_TOKEN}}"
+#        dotnet pack "BepuPhysics" -c Release
+#        dotnet pack "BepuUtilities" -c Release
+#        dotnet nuget push "**/*.nupkg" -s "github" -k "${{secrets.GITHUB_TOKEN}}" --skip-duplicate
+#        dotnet nuget push "**/*.nupkg" -s "https://api.nuget.org/v3/index.json" -k "${{secrets.NUGET_KEY}}" --skip-duplicate