1.2.0a6

Changes since 1.2.0a5

• release: alpha bump langgraph 1.2.0a6 (#7697)
• feat(langgraph): forward kwargs through stream_events(version="v3") (#7696)
• chore(deps): bump the minor-and-patch group across 1 directory with 6 updates (#7675)
• chore(deps): bump notebook from 7.5.2 to 7.5.6 in /libs/langgraph (#7657)