Add experimental unstable dependencies to conda CI

.github/workflows/tests_conda.yml

@@ -14,9 +14,14 @@ jobs:
         python-version: [ "3.8", "3.9", "3.10", "3.11", "3.12" ]
         os: [windows-latest, ubuntu-latest, macos-latest]
         platform: [x64, x32]
+        experimental: [false]
         exclude:
           - os: macos-latest  
             platform: x32
+        include:
+          - python-version: "3.12"
+            os: "ubuntu-latest"
+            experimental: true
 
     steps:
     - uses: actions/checkout@v4
@@ -31,6 +36,16 @@ jobs:
           cython>=0.29.20
           pytest
           pytest-cov
+          -
+    - name: Install unstable dependencies
+      if: matrix.experimental == true
+      shell: bash -l {0}
+      run: |
+        python -m pip install \
+        --index-url https://pypi.anaconda.org/scientific-python-nightly-wheels/simple/ \
+        --trusted-host pypi.anaconda.org \
+        --no-deps --pre --upgrade \
+        numpy;
 
     - name: Install cftime
       shell: bash -l {0}