Merge pull request w7corp#1596 from wannanbigpig/microMerchant

fix bug

默认日志级别为 debug

Merge pull request w7corp#1590 from overtrue/analysis-zGpeJo

Apply fixes from StyleCI

Fix cache w7corp#1580

Merge pull request w7corp#1572 from overtrue/analysis-XNnOWG

Apply fixes from StyleCI

Merge pull request w7corp#1568 from wannanbigpig/new_feature

新增了setCertificate方法

Merge pull request w7corp#1555 from overtrue/revert-1554-guzzle/handler

Revert "Accept guzzle handler object"

Merge pull request w7corp#1554 from overtrue/guzzle/handler

Accept guzzle handler object

Bugfix.

Merge pull request w7corp#1509 from overtrue/revert-1508-dependabot/c…

…omposer/phpunit/phpunit-approx-8.0

Revert "Update phpunit/phpunit requirement from ~6.0 to ~8.0"