update changelog for 1.8 version.
+## 1.8
+
+- Feature: Fully support Redis6!
+ - Support `STRALGO` command.
+ - `MIGRATE` command now support `AUTH2`.
+ - DISABLE `hello` command, IRedis not support RESP3.
+
### 1.7.4
- Bugfix: Lock wcwidth's version on `1.9.0`. Fix binary build.
