fix(ci): update Python version matrix and add numpy/scikit-image constraints for testing

Author: PierreRaybaut

.github/workflows/test_pyqt5.yml

@@ -6,6 +6,7 @@
 name: Install and Test on Ubuntu (latest) with PyQt5
 
 on:
+  workflow_dispatch:
   push:
     branches: [ "main", "develop", "release" ]
   pull_request:
@@ -22,6 +23,22 @@ jobs:
       fail-fast: false
       matrix:
         python-version: ["3.9", "3.13"]
+        include:
+          # Baseline that used to pass (from 2025-12-19)
+          - python-version: "3.13"
+            numpy: "2.3.5"
+            skimage: "0.25.2"
+          # Newer versions that appeared on 2026-01-05
+          - python-version: "3.13"
+            numpy: "2.4.0"
+            skimage: "0.26.0"
+          # Cross-checks to identify the culprit
+          - python-version: "3.13"
+            numpy: "2.3.5"
+            skimage: "0.26.0"
+          - python-version: "3.13"
+            numpy: "2.4.0"
+            skimage: "0.25.2"
 
     steps:
     - uses: actions/checkout@v4
@@ -36,6 +53,15 @@ jobs:
         python -m pip install --upgrade pip
         python -m pip install ruff pytest
         pip install PyQt5
+
+        # --- quick bisect constraints (only active for the matrix entries that define them)
+        if [ -n "${{ matrix.numpy }}" ] || [ -n "${{ matrix.skimage }}" ]; then
+          echo "numpy==${{ matrix.numpy }}" > constraints.txt
+          echo "scikit-image==${{ matrix.skimage }}" >> constraints.txt
+          python -m pip install -c constraints.txt "numpy==${{ matrix.numpy }}" "scikit-image==${{ matrix.skimage }}"
+        fi
+        # ---
+
         if [ "${{ github.ref_name }}" = "develop" ]; then
            # Clone and install development versions of key dependencies with editable install
            cd ..