CI: bump remaining workflow actions off deprecated Node 20

Update the active workflows to current major releases (all Node 24):
  ci-build-test.yml:    checkout v4->v7 (x6)
  build_nectarcloud.yml: checkout v4->v7, upload-artifact v4->v7
  build_binder_image.yml: checkout v4->v7, docker/setup-buildx-action v3->v4,
                          docker/login-action v3->v4, docker/build-push-action v5->v7

The disabled *.yml.old workflows are left as-is (not run by Actions).

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

Author: Lutz Gross

.github/workflows/build_binder_image.yml

@@ -19,20 +19,20 @@ jobs:
 
     steps:
       - name: Checkout code
-        uses: actions/checkout@v4
+        uses: actions/checkout@v7
 
       - name: Set up Docker Buildx
-        uses: docker/setup-buildx-action@v3
+        uses: docker/setup-buildx-action@v4
 
       - name: Login to DockerHub
         if: github.event_name != 'pull_request'
-        uses: docker/login-action@v3
+        uses: docker/login-action@v4
         with:
           username: ${{ secrets.DOCKERHUB_USERNAME }}
           password: ${{ secrets.DOCKERHUB_TOKEN }}
 
       - name: Build and push Docker image
-        uses: docker/build-push-action@v5
+        uses: docker/build-push-action@v7
         with:
           context: .
           file: ./binder/DockerfileMain

.github/workflows/build_nectarcloud.yml

@@ -14,7 +14,7 @@ jobs:
 
     steps:
       - name: Checkout code
-        uses: actions/checkout@v4
+        uses: actions/checkout@v7
         with:
           submodules: recursive
 
@@ -38,7 +38,7 @@ jobs:
 
       - name: Upload test results
         if: always()
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v7
         with:
           name: test-results
           path: testout.log

.github/workflows/ci-build-test.yml

@@ -34,7 +34,7 @@ jobs:
 
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v7
 
       - name: Install system dependencies
         run: |
@@ -129,7 +129,7 @@ jobs:
 
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v7
 
       - name: Install Homebrew dependencies
         run: |
@@ -223,7 +223,7 @@ jobs:
         run: dnf install -y git
 
       - name: Checkout repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v7
 
       - name: Verify checkout
         run: |
@@ -306,7 +306,7 @@ jobs:
         run: pacman -Sy --noconfirm git
 
       - name: Checkout repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v7
 
       - name: Install system dependencies
         run: |
@@ -387,7 +387,7 @@ jobs:
         run: zypper --non-interactive install git
 
       - name: Checkout repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v7
 
       - name: Install system dependencies
         run: |
@@ -465,7 +465,7 @@ jobs:
         run: dnf install -y git
 
       - name: Checkout repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v7
 
       - name: Enable repositories
         run: |