ci: split out py3.13 to different workflow

Our PR now uses `pull_request_target` to allow coverage info, and we
don't want to have both `pull_request_target` and `pull_request` in the
same workflow.

.github/workflows/ci-internal.yml

@@ -0,0 +1,55 @@
+name: Continuous builds: py3.13
+
+on:
+  push:
+    branches:
+      - master
+      - development
+      - experimental
+      - 'test*'
+  pull_request:
+    branches:
+      - master
+      - development
+      - experimental
+      - 'test*'
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+    permissions:
+      pull-requests: write
+    strategy:
+      matrix:
+        python-version: ["3.13.0-beta.2"]
+      fail-fast: false
+
+    steps:
+
+    - uses: actions/checkout@v4
+    - name: Set up Python  ${{ matrix.python-version }}
+      uses: actions/setup-python@v5
+      with:
+        python-version:  ${{ matrix.python-version }}
+
+    - name: Print refs
+      run: |
+        echo "github.ref is: ${{ github.ref }}"
+        echo "github.base_ref is: ${{ github.base_ref }}"
+
+    - name: Upgrade pip, install deps
+      run: |
+        python -m pip install --upgrade pip
+        pip install numpy<2.0.0 # due to lingering issues with other modules
+        pip install .[dev]
+
+    - name: List packages so far
+      run: |
+        pip list
+
+    - name: Run tests
+      run: |
+        pynml -h
+
+        ./test-ghactions.sh -neuron

.github/workflows/ci.yml

@@ -13,12 +13,6 @@ on:
       - development
       - experimental
       - 'test*'
-  pull_request:
-    branches:
-      - master
-      - development
-      - experimental
-      - 'test*'
 
 jobs:
   build: