Update slack link

[rohitgr7]

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Fixes #<issue_number>

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[Borda]

pls check when generating this link that it is without expiration 🐰

[rohitgr7]

pls check when generating this link that it is without expiration 🐰

I didn't generate this. Can you confirm with Will? the old one seems to be without any expiration date since it's still working.

[Borda]

pls check when generating this link that it is without expiration rabbit

I didn't generate this. Can you confirm with Will? the old one seems to be without any expiration date since it's still working.

it is correct, just as discussed, lets create and use a permanent one :)

[akihironitta]

pls check when generating this link that it is without expiration 🐰

I remember even if it's generated without expiration, it'll be expired after a certain number of people join Slack with the link, so I guess maybe we need to have a permanent proxy link and update its redirection occasionally.