Fix #1251 Upgrade the minimum version of "ws" package

[seratch]

Summary

This pull request fixes #1251 by upgrading the minimum version of "ws" package in socket-mode / rtm-api packages.

• https://github.com/websockets/ws/releases
• https://www.npmjs.com/package/ws

As you can see in the GitHub release page, a number of bug fixes have been applied in ws@7 series. As most of Socket Mode clients won't have version conflict issues on "ws" package with other parts of those apps, encouraging developers to use the latest patch version should be just safe enough.

"ws" project recently released a new major version v8 (the latest minor is v8.2). We haven't received any reports about the compatibility. Just in case, I did some tests with ws@8 today but didn't detect any issues so far. For this reason, I think that we don't need to limit the upper to v7.x so far.

Requirements (place an x in each [ ])

• I've read and understood the Contributing Guidelines and have done my best effort to follow them.
• I've read and agree to the Code of Conduct.

[mwbrooks]

Thanks for testing with [email protected] as well. I agree that we can keep it at [email protected] until we there's a stronger reason to force 8.0+

[seratch]

Thanks. v8 is one month old. Holding off forcing v8 should be fine so far.

[300LiterPropofol]

Sorry that I have a confusion here. I reinstalled @slack/bolt but the ws version in package-lock.json is till 7. And I manually npm install [email protected] but I found the dependency of @slack/socket-mode in is still ws@7. How can I use ws8 in slack bolt here?