CI: bump GitHub Actions to Node 24-compatible majors

GitHub will force JS actions to Node 24 on June 2nd, 2026, and remove
Node 20 from runners on September 16th, 2026. Bumps the four actions
called out in the runner deprecation warning:

- actions/checkout v4 → v5
- actions/setup-dotnet v4 → v5
- actions/upload-artifact v4 → v6
- signpath/github-action-submit-signing-request v1 → v2

Matches the bump PerformanceStudio just made for the same reason.
dorny/paths-filter@v3 not in the warning, left as-is.

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

Author: erikdarlingdata

.github/workflows/build.yml

@@ -18,7 +18,7 @@ jobs:
     runs-on: windows-latest
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
 
       - name: Detect changed paths
         id: filter
@@ -46,7 +46,7 @@ jobs:
               - 'upgrades/**'
 
       - name: Setup .NET 8.0
-        uses: actions/setup-dotnet@v4
+        uses: actions/setup-dotnet@v5
         with:
           dotnet-version: 8.0.x
           cache: true
@@ -132,30 +132,30 @@ jobs:
       - name: Upload Dashboard for signing
         if: github.event_name == 'release'
         id: upload-dashboard
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v6
         with:
           name: Dashboard-unsigned
           path: publish/Dashboard/
 
       - name: Upload Lite for signing
         if: github.event_name == 'release'
         id: upload-lite
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v6
         with:
           name: Lite-unsigned
           path: publish/Lite/
 
       - name: Upload Installer for signing
         if: github.event_name == 'release'
         id: upload-installer
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v6
         with:
           name: Installer-unsigned
           path: publish/Installer/
 
       - name: Sign Dashboard
         if: github.event_name == 'release'
-        uses: signpath/github-action-submit-signing-request@v1
+        uses: signpath/github-action-submit-signing-request@v2
         with:
           api-token: '${{ secrets.SIGNPATH_API_TOKEN }}'
           organization-id: '7969f8b6-d946-4a74-9bac-a55856d8b8e0'
@@ -168,7 +168,7 @@ jobs:
 
       - name: Sign Lite
         if: github.event_name == 'release'
-        uses: signpath/github-action-submit-signing-request@v1
+        uses: signpath/github-action-submit-signing-request@v2
         with:
           api-token: '${{ secrets.SIGNPATH_API_TOKEN }}'
           organization-id: '7969f8b6-d946-4a74-9bac-a55856d8b8e0'
@@ -181,7 +181,7 @@ jobs:
 
       - name: Sign Installer
         if: github.event_name == 'release'
-        uses: signpath/github-action-submit-signing-request@v1
+        uses: signpath/github-action-submit-signing-request@v2
         with:
           api-token: '${{ secrets.SIGNPATH_API_TOKEN }}'
           organization-id: '7969f8b6-d946-4a74-9bac-a55856d8b8e0'

.github/workflows/check-version-bump.yml

@@ -10,7 +10,7 @@ jobs:
 
     steps:
       - name: Checkout PR branch
-        uses: actions/checkout@v4
+        uses: actions/checkout@v5
 
       - name: Get PR version
         id: pr
@@ -21,7 +21,7 @@ jobs:
           Write-Host "PR version: $version"
 
       - name: Checkout main
-        uses: actions/checkout@v4
+        uses: actions/checkout@v5
         with:
           ref: main
           path: main-branch

.github/workflows/nightly.yml

@@ -15,7 +15,7 @@ jobs:
     outputs:
       has_changes: ${{ steps.check.outputs.has_changes }}
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
         with:
           ref: dev
           fetch-depth: 0
@@ -38,12 +38,12 @@ jobs:
     runs-on: windows-latest
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
         with:
           ref: dev
 
       - name: Setup .NET 8.0
-        uses: actions/setup-dotnet@v4
+        uses: actions/setup-dotnet@v5
         with:
           dotnet-version: 8.0.x
           cache: true

.github/workflows/sql-validation.yml

@@ -41,7 +41,7 @@ jobs:
           --health-retries 15
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
 
       - name: Install sqlcmd
         run: |