Update wechaty requirement from ~=0.5dev1 to ~=0.6

Updates the requirements on [wechaty](https://github.com/wechaty/python-wechaty) to permit the latest version.
- [Release notes](https://github.com/wechaty/python-wechaty/releases)
- [Commits](https://github.com/wechaty/python-wechaty/commits)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Author: dependabot-preview[bot]

requirements.txt

@@ -1 +1 @@
-wechaty~=0.5dev1
+wechaty~=0.6