main: Update apache/spark Docker tag to v3.5.6 (#1791)

Author: renovate-bot

getting-started/eclipselink/docker-compose.yml

@@ -65,7 +65,7 @@ services:
     entrypoint: '/bin/sh -c "chmod +x /polaris/create-catalog.sh && /polaris/create-catalog.sh"'
 
   spark-sql:
-    image: apache/spark:3.5.5-java17-python3
+    image: apache/spark:3.5.6-java17-python3
     depends_on:
       polaris-setup:
         condition: service_completed_successfully

getting-started/jdbc/docker-compose.yml

@@ -68,7 +68,7 @@ services:
     entrypoint: '/bin/sh -c "chmod +x /polaris/create-catalog.sh && /polaris/create-catalog.sh"'
 
   spark-sql:
-    image: apache/spark:3.5.5-java17-python3
+    image: apache/spark:3.5.6-java17-python3
     depends_on:
       polaris-setup:
         condition: service_completed_successfully