Fix OpenCV Dependabot compatibility bound

.github/dependabot.yml

@@ -15,17 +15,17 @@ updates:
           - "minor"
           - "patch"
     # The `all` extra must remain jointly resolvable. These candidates violate
-    # upstream constraints: TrustMark still requires NumPy 1.x, OpenCV 5 requires
-    # NumPy 2 on newer Python versions, and this project keeps tokenizers below
-    # 0.23 for the stable Transformers path. Keep Dependabot on the compatible
-    # lines until those constraints move.
+    # upstream constraints: TrustMark still requires NumPy 1.x, OpenCV 4.13+
+    # requires NumPy 2 on newer Python versions, and this project keeps tokenizers
+    # below 0.23 for the stable Transformers path. Keep Dependabot on the
+    # compatible lines until those constraints move.
     ignore:
       - dependency-name: "numpy"
         versions:
           - ">=2"
       - dependency-name: "opencv-python-headless"
         versions:
-          - ">=5"
+          - ">=4.13"
       - dependency-name: "tokenizers"
         versions:
           - ">=0.23"

tests/test_dependabot.py

@@ -0,0 +1,11 @@
+"""Regression tests for Dependabot compatibility constraints."""
+
+from pathlib import Path
+
+
+def test_dependabot_blocks_opencv_releases_that_require_numpy_2() -> None:
+    config = Path(".github/dependabot.yml").read_text()
+
+    opencv_ignore = config.split('dependency-name: "opencv-python-headless"', maxsplit=1)[1]
+    assert '"<4.13"' not in opencv_ignore
+    assert '- ">=4.13"' in opencv_ignore