Retry on Rocky Linux Python install (#16190)

I'm not sure why these mirrors have been flaky lately.

e.g.
https://github.com/astral-sh/uv/actions/runs/18346934817/job/52256348387?pr=16182

Author: zanieb

.github/workflows/ci.yml

@@ -2201,12 +2201,24 @@ jobs:
       - name: "Install Python"
         if: matrix.rocky-version == '8'
         run: |
-          dnf install python39 python39-pip which -y
+          for i in {1..5}; do
+            dnf install python39 python39-pip which -y && break || { echo "Attempt $i failed, retrying in 10 seconds..."; sleep 10; }
+            if [ $i -eq 5 ]; then
+              echo "Failed to install Python after 5 attempts"
+              exit 1
+            fi
+          done
 
       - name: "Install Python"
         if: matrix.rocky-version == '9'
         run: |
-          dnf install python3.9 python3.9-pip which -y
+          for i in {1..5}; do
+            dnf install python3.9 python3.9-pip which -y && break || { echo "Attempt $i failed, retrying in 10 seconds..."; sleep 10; }
+            if [ $i -eq 5 ]; then
+              echo "Failed to install Python after 5 attempts"
+              exit 1
+            fi
+          done
 
       - name: "Install Python"
         if: matrix.rocky-version == '10'