test: Increase PyMilvus version to 2.6.11rc18 for 2.6 branch#48541

pymilvus-bot wants to merge 1 commit intomilvus-io:2.6milvus-io/milvus:2.6from

pymilvus-bot:bot/pymilvus-update-for-2-6-2.6.11rc18-20260326071836pymilvus-bot/milvus:bot/pymilvus-update-for-2-6-2.6.11rc18-20260326071836Copy head branch name to clipboard