Slack OIDC is not displayed properly

[worldofprasanna]

Bug report

Describe the bug

I have setup Slack_OIDC Provider as the default Slack provider is deprecated and I couldn't create it in Supabase. But in the Auth component, it is rendered as "Slack_oidc" and without any Logo.

To Reproduce

1. Specify slack_oidc provider in the list
2. Sign in button will be generated but without logo and proper text

Eg:
<Auth
supabaseClient={supabase}
appearance={{ theme: ThemeSupa }}
theme="default"
providers={["google", "slack_oidc"]}
/>

Expected behavior

I expect the Slack Login button to be generated with the proper logo and name as "Slack" (not as Slack_oidc)

Screenshots

Additional context

A similar issue occurred for LinkedIn also - #234

Happy to give a similar PR for Slack OIDC as well.