ci: add Slack notification for maintainer PRs#2155

felixweinberger wants to merge 1 commit intov1.xmodelcontextprotocol/python-sdk:v1.xfrom

fweinberger/pr-notify-slack-v1xmodelcontextprotocol/python-sdk:fweinberger/pr-notify-slack-v1xCopy head branch name to clipboard