updating changelog in master to reflect start of 1.7 release process (#3728)

Signed-off-by: Ken Haines <[email protected]>

Author: khaines

CHANGELOG.md

@@ -2,6 +2,9 @@
 
 ## master / unreleased
 
+
+## 1.7.0 in progress
+
 * [CHANGE] FramedSnappy encoding support has been removed from Push and Remote Read APIs. This means Prometheus 1.6 support has been removed and the oldest Prometheus version supported in the remote write is 1.7. #3682
 * [CHANGE] Ruler: removed the flag `-ruler.evaluation-delay-duration-deprecated` which was deprecated in 1.4.0. Please use the `ruler_evaluation_delay_duration` per-tenant limit instead. #3693
 * [CHANGE] Removed the flags `-<prefix>.grpc-use-gzip-compression` which were deprecated in 1.3.0: #3693