CI: include test against nightly numpy

.github/workflows/test_code.yml

@@ -13,7 +13,15 @@ jobs:
       matrix:
         os: [ubuntu-latest, windows-latest]
         python-version: ["3.8", "3.12"]
+        experimental: [false]
+        include:
+          - python-version: "3.12"
+            os: "ubuntu-latest"
+            experimental: true
       fail-fast: false
+    defaults:
+      run:
+        shell: bash -l {0}
 
     steps:
     - uses: actions/checkout@v4
@@ -27,10 +35,12 @@ jobs:
           --file requirements.txt
           --file requirements-dev.txt
 
+    - name: Install nightly versions of dependencies
+      if: matrix.experimental == true
+      run: python -m pip install --pre --index-url https://pypi.anaconda.org/scientific-python-nightly-wheels/simple --extra-index-url https://pypi.org/simple numpy pandas shapely -U
+
     - name: Install folium from source
-      shell: bash -l {0}
       run: python -m pip install -e . --no-deps --force-reinstall
 
     - name: Code tests
-      shell: bash -l {0}
       run: python -m pytest -vv --ignore=tests/selenium