Fix slack link, stop inspecting it

Slack returns 403 for linkspector, it will never work.

Also, used wrong invite somehow, just re-copied this
from the web site.  But the other one worked, it was just
linkspector couldn't access it in CI.

Author: handrews

.linkspector.yml

@@ -11,6 +11,7 @@ files:
   - style-guide.md
   - TOB.md
 ignorePatterns:
+  - pattern: 'slack.com'  # Slack invite links 403 with linkspector
   - pattern: 'clientdomain.com'
   - pattern: 'example.org'
   - pattern: 'https://www.w3.org/TR/xml-names11/'

CONTRIBUTING.md

@@ -390,7 +390,7 @@ The triage team keeps an eye on the backlog and closes issues and discussions th
 
 To get in touch with other people on the project, ask questions, or anything else:
 
-- Find us [on the OpenAPI Slack](https://join.slack.com/t/open-api/shared_invite/zt-45j57ones-BcErzGqJKA5Ib4wrM83Cgw).
+- Find us [on the OpenAPI Slack](https://open-api.slack.com/join/shared_invite/zt-45hwx39lu-L5kfOMIyFc4qt0v~FPGaXQ).
 - Start a [GitHub Discussion](https://github.com/OAI/OpenAPI-Specification/discussions/).
 - Join one of our weekly meetings by checking the [issues list for an upcoming meetings](https://github.com/OAI/OpenAPI-Specification/issues?q=is%3Aissue%20state%3Aopen%20label%3AHousekeeping).