deps: bump slack-sdk from 3.28.0 to 3.31.0 in /data/src#800

nlebovits merged 1 commit intostagingCodeForPhilly/clean-and-green-philly:stagingfrom

dependabot/pip/data/src/staging/slack-sdk-3.31.0CodeForPhilly/clean-and-green-philly:dependabot/pip/data/src/staging/slack-sdk-3.31.0Copy head branch name to clipboard