chore: Update new slack url

[Achanandhi-M]

Description

I have updated the slack url

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• My changes generate no new warnings
• I have checked my code and corrected any misspellings
• I have signed the commit message to agree to Developer Certificate of Origin (DCO) (to certify that you wrote or otherwise have the right to submit your contribution to the project.) by adding "--signoff" to my git commit command.

[keploy]

Nice Pr 😄. We currently support Unit Test Generation only for Go projects.
Stay tuned – support for more languages is coming soon! 🚀