Add X-Accel-Buffering: no header to GAE keeps connecion alive for SSE
Add X-Accel-Buffering: no header to GAE keeps connecion alive for SSE

GoogleChromeLabs/lighthousebot,ebidel/lighthouse-ci,ebidel/lighthouse-ci,GoogleChromeLabs/lighthousebot,GoogleChromeLabs/lighthousebot,ebidel/lighthouse-ci