CI: bump actions off deprecated Node 20 to latest majors

GitHub is deprecating Node 20 on runners. Pin each action to its
current major (all run on Node 24):
- actions/checkout        v4 -> v7
- actions/setup-dotnet    v4 -> v6
- actions/upload-pages-artifact v3 -> v5
- actions/deploy-pages    v4 -> v5

Applies to both the Pages deploy and NuGet publish workflows.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: peopleworks

.github/workflows/deploy-pages.yml

@@ -20,10 +20,10 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v7
 
       - name: Setup .NET
-        uses: actions/setup-dotnet@v4
+        uses: actions/setup-dotnet@v6
         with:
           dotnet-version: "10.0.x"
 
@@ -39,7 +39,7 @@ jobs:
       - name: SPA fallback
         run: cp publish/wwwroot/index.html publish/wwwroot/404.html
 
-      - uses: actions/upload-pages-artifact@v3
+      - uses: actions/upload-pages-artifact@v5
         with:
           path: publish/wwwroot
 
@@ -51,4 +51,4 @@ jobs:
       url: ${{ steps.deployment.outputs.page_url }}
     steps:
       - id: deployment
-        uses: actions/deploy-pages@v4
+        uses: actions/deploy-pages@v5

.github/workflows/nuget.yml

@@ -12,10 +12,10 @@ jobs:
   publish:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v7
 
       - name: Setup .NET
-        uses: actions/setup-dotnet@v4
+        uses: actions/setup-dotnet@v6
         with:
           dotnet-version: "10.0.x"