Fix division by zero error in ecosystem check (#11469)

e.g.
https://github.com/astral-sh/ruff/actions/runs/9144809516/job/25143076896?pr=11468

<img width="1388" alt="Screenshot 2024-05-19 at 12 02 15 AM"
src="https://github.com/astral-sh/ruff/assets/2586601/0df7cbcd-712c-4ea9-96f5-73f871570525">

python/ruff-ecosystem/ruff_ecosystem/check.py

@@ -145,7 +145,20 @@ def markdown_check_result(result: Result) -> str:
 
         # Limit the number of items displayed per project to between 10 and 50
         # based on the proportion of total changes present in this project
-        max_display_per_project = max(10, int((project_changes / total_changes) * 50))
+        max_display_per_project = max(
+            10,
+            int(
+                (
+                    # TODO(zanieb): We take the `max` here to avoid division by zero errors where
+                    # `total_changes` is zero but `total_affected_rules` is non-zero so we did not
+                    # skip display. This shouldn't really happen and indicates a problem in the
+                    # calculation of these values. Instead of skipping entirely when `total_changes`
+                    # is zero, we'll attempt to report the results to help diagnose the problem.
+                    project_changes / max(total_changes, 1)
+                )
+                * 50
+            ),
+        )
 
         # Limit the number of items displayed per rule to between 5 and the max for
         # the project based on the number of rules affected (less rules, more per rule)