pull docker image build out of the os matrix

Author: kevinjqliu

.github/workflows/python-ci.yml

@@ -67,8 +67,33 @@ jobs:
     - name: Generate coverage report (85%) # Coverage threshold should only increase over time — never decrease it!
       run: COVERAGE_FAIL_UNDER=85 make coverage-report
 
+  build-docker-images:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v6
+
+    - name: Set up Docker Buildx
+      uses: docker/setup-buildx-action@v3
+
+    - name: Build and cache Spark image
+      uses: docker/build-push-action@v6
+      with:
+        context: dev/spark
+        tags: pyiceberg-spark:latest
+        cache-from: type=gha,scope=spark
+        cache-to: type=gha,mode=max,scope=spark
+
+    - name: Build and cache Hive image
+      uses: docker/build-push-action@v6
+      with:
+        context: dev/hive
+        tags: pyiceberg-hive:latest
+        cache-from: type=gha,scope=hive
+        cache-to: type=gha,mode=max,scope=hive
+
   integration-test:
     runs-on: ubuntu-latest
+    needs: build-docker-images
     strategy:
       matrix:
         python: ['3.10', '3.11', '3.12', '3.13']
@@ -88,23 +113,21 @@ jobs:
     - name: Set up Docker Buildx
       uses: docker/setup-buildx-action@v3
 
-    - name: Build and cache Spark image
+    - name: Build Spark image (from cache)
       uses: docker/build-push-action@v6
       with:
         context: dev/spark
         load: true
         tags: pyiceberg-spark:latest
         cache-from: type=gha,scope=spark
-        cache-to: type=gha,mode=max,scope=spark
 
-    - name: Build and cache Hive image
+    - name: Build Hive image (from cache)
       uses: docker/build-push-action@v6
       with:
         context: dev/hive
         load: true
         tags: pyiceberg-hive:latest
         cache-from: type=gha,scope=hive
-        cache-to: type=gha,mode=max,scope=hive
 
     - name: Run integration tests with coverage
       run: COVERAGE=1 make test-integration