add defaultAuthPlugin parameter

update changelog for Version 1.7 (go-sql-driver#1376)

Release v1.6.0 (go-sql-driver#1197)

* Release v1.6.0

* v1.6.0 is released on 2021-04-01

Release v1.5.0 (go-sql-driver#1047)

* CHANGELOG: include v1.4.1

* Release v1.5.0

Release v1.4.1

Release v1.4.0 (go-sql-driver#809)

Version 1.3.0

Release v1.3 (go-sql-driver#517)

* Update CHANGELOG
* README: Removed most recent version and build status

Version 1.2.0

Release v1.2