fix(ci): create virtualenv for maturin develop in Python bindings job

maturin develop requires a virtualenv or conda environment. The CI step
was installing maturin globally which caused it to fail with
"Couldn't find a virtualenv or conda environment".

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: mivertowski

.github/workflows/ci.yml

@@ -284,13 +284,21 @@ jobs:
         with:
           python-version: ${{ matrix.python-version }}
 
-      - name: Install maturin and pytest
-        run: pip install maturin pytest
+      - name: Create virtualenv and install tools
+        working-directory: RustKernels/RustKernels/crates/rustkernel-python
+        run: |
+          python -m venv .venv
+          source .venv/bin/activate
+          pip install maturin pytest
 
       - name: Build and install Python package
         working-directory: RustKernels/RustKernels/crates/rustkernel-python
-        run: maturin develop --features full
+        run: |
+          source .venv/bin/activate
+          maturin develop --features full
 
       - name: Run Python tests
         working-directory: RustKernels/RustKernels/crates/rustkernel-python
-        run: pytest tests/ -v
+        run: |
+          source .venv/bin/activate
+          pytest tests/ -v