ci: use non-EOL runtimes and current action versions

Bump the CI workflow to avoid EOL/outdated versions:
- actions/checkout, setup-node, setup-python -> @v7 (were @v4/@v5)
- drop EOL Node 20 from the matrix; test on Node 22.x (Active LTS) + 24.x
Python stays on 3.11 (supported, not EOL). Verified the JS builds/smoke/tests
pass locally on Node 24.

Author: jhamon

.github/workflows/ci.yml

@@ -19,10 +19,10 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        node-version: ['20.x', '22.x']
+        node-version: ['22.x', '24.x']
     steps:
-      - uses: actions/checkout@v4
-      - uses: actions/setup-node@v4
+      - uses: actions/checkout@v7
+      - uses: actions/setup-node@v7
         with:
           node-version: ${{ matrix.node-version }}
           cache: npm
@@ -37,8 +37,8 @@ jobs:
     name: Backend (FastAPI)
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
-      - uses: actions/setup-python@v5
+      - uses: actions/checkout@v7
+      - uses: actions/setup-python@v7
         with:
           python-version: '3.11'
           cache: pip
@@ -54,8 +54,8 @@ jobs:
     runs-on: ubuntu-latest
     continue-on-error: true
     steps:
-      - uses: actions/checkout@v4
-      - uses: actions/setup-node@v4
+      - uses: actions/checkout@v7
+      - uses: actions/setup-node@v7
         with:
           node-version: '22.x'
           cache: npm