minor #51486 Update the list of sponsors for Symfony 6.4 🙏 (nicolas-grekas)

This PR was merged into the 6.4 branch.

Discussion
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Update the list of sponsors for Symfony 6.4 🙏

| Q             | A
| ------------- | ---
| Branch?       | 6.4
| Bug fix?      | no
| New feature?  | no
| Deprecations? | no
| Tickets       | -
| License       | MIT
| Doc PR        | -

Symfony 6.4 LTS is sponsored by:
- packagist.com 📦 `@naderman` `@Seldaek`
- SensioLabs 💚

But also by SymfonyCasts for the Security components `@weaverryan`

🙏

We are [looking for more sponsors](https://symfony.com/blog/symfony-sponsoring-program) !

I invite anyone interested in sponsoring any versions x components of Symfony to [reach us ASAP](https://symfony.com/support?product=SFB#products) (I removed sponsors of 6.3 but I'm sure some of them would be happy to renew ;) .)

(Note that I'm personally going to be AFK for the next 2 weeks 🌴 .)

Commits
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b6699ca164 Update the list of sponsors for Symfony 6.4 🙏

Author: fabpot

README.md

@@ -15,7 +15,7 @@ $ composer require symfony/security-http
 Sponsor
 -------
 
-The Security component for Symfony 6.3 is [backed][1] by [SymfonyCasts][2].
+The Security component for Symfony 6.4 is [backed][1] by [SymfonyCasts][2].
 
 Learn Symfony faster by watching real projects being built and actively coding
 along with them. SymfonyCasts bridges that learning gap, bringing you video