Upgrade axios to resolve CVE-2023-45857

[helzahalim]

Current @slack/bolt@3.14.0 is using axios@0.27.2. There is Cross-site Request Forgery (CSRF) vulnerability on version 1.5 and lower.

Requirements

Axios version should be upgraded to 1.6.0 to address CVE-2023-45857

[filmaj]

Note that the vulnerability is limited to CSRF only. The only instance we use axios in bolt is for creating a helper utility method to respond to events with a message from a Slack-server-pushed event. I do not believe CSRF is a viable vector of attack in this situation.

That said, makes sense to update the dependency. Will take a look at the relevant PR (#1986).

[filmaj]

Resolved in #1986.