fix: upgrade deprecated GitHub Actions to v4/v5 and fix MCP test job

actions/upload-artifact@v3 is fully deprecated and causes instant CI
failure. Also upgrades checkout, setup-python, cache, github-script,
and codecov actions to their latest major versions to resolve Node.js 20
deprecation warnings. Adds missing pytest install to MCP Vector DB test
job and pins ruff>=0.15 in CI to match local tooling.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.github/workflows/test-vector-dbs.yml

@@ -35,10 +35,10 @@ jobs:
       PYTHON_VERSION: ${{ matrix.python-version }}
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
 
     - name: Set up Python
-      uses: actions/setup-python@v4
+      uses: actions/setup-python@v5
       with:
         python-version: ${{ env.PYTHON_VERSION }}
 
@@ -76,7 +76,7 @@ jobs:
         "
 
     - name: Upload test package
-      uses: actions/upload-artifact@v3
+      uses: actions/upload-artifact@v4
       with:
         name: test-package-${{ env.ADAPTOR_NAME }}-py${{ env.PYTHON_VERSION }}
         path: test_skill-${{ env.ADAPTOR_NAME }}.json
@@ -87,16 +87,17 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
 
     - name: Set up Python 3.12
-      uses: actions/setup-python@v4
+      uses: actions/setup-python@v5
       with:
         python-version: '3.12'
 
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip
+        pip install pytest
         pip install -e .
 
     - name: Run MCP vector DB tests
@@ -110,10 +111,10 @@ jobs:
     needs: [test-adaptors, test-mcp-tools]
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
 
     - name: Set up Python 3.12
-      uses: actions/setup-python@v4
+      uses: actions/setup-python@v5
       with:
         python-version: '3.12'