[firebase-release] Removed change log and reset repo after 3.8.0 release

Author: google-oss-bot

CHANGELOG.md

@@ -1,12 +0,0 @@
-- Fixes error when last argument to logger methods is `null`. (#716)
-- Adds eight new available regions:
-  - `us-west2`
-  - `us-west3`
-  - `us-west4`
-  - `europe-west6`
-  - `asia-northeast2`
-  - `northamerica-northeast1`
-  - `southamerica-east1`
-  - `australia-southeast1`
-- No longer throw errors for unrecognized regions (deploy will error instead).
-- Fixes error where `snap.ref` in database functions did not work when using the Emulator Suite (#726)