v1.21.6

Changelog

acb55dc Release websocket.Client deadlock fix to all users (#1242)
4db2ecb Small connect fixes for billing meters (#1246)
8d33a69 [listen] logging improvements (#1229)
5be357c [trigger] add billing trigger (#1230)
6c259f0 fix: link to thin event in local listener view (#1241)
2f1cc41 fix: only trigger pager duty alert if install actually fails (#1237)
d5651bf fix: show pretty error when trying to create meter event stream or session (#1243)
3bf89da fix: use meter-events.stripe.com instead of events.stripe.com (#1244)
46d3aad make connect blue in listen output (#1248)
667f802 set stripe-version in v1 billing meter triggers (#1251)
01fb13a supply more URL endpoint details to server (#1247)