minor symfony#61016 Update sponsors for Symfony 7.3 (mttsch)

This PR was merged into the 7.3 branch.

Discussion
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Update sponsors for Symfony 7.3

| Q             | A
| ------------- | ---
| Branch?       | 7.3
| Bug fix?      | yes
| New feature?  | no
| Deprecations? | no
| Issues        |
| License       | MIT

The sponsor is taken from https://symfony.com/blog/symfony-7-3-curated-new-features and https://symfony.com/releases/7.3.

Commits
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dc0b726 Update sponsors for Symfony 7.3

Author: fabpot

README.md

@@ -17,20 +17,13 @@ Installation
 Sponsor
 -------
 
-Symfony 7.2 is [backed][27] by
-- [Sulu][29]
-- [Rector][30]
+Symfony 7.3 is [backed][27] by
+- [Les-Tilleuls.coop][29]
 
-**Sulu** is the CMS for Symfony developers. It provides pre-built content-management
-features while giving developers the freedom to build, deploy, and maintain custom
-solutions using full-stack Symfony. Sulu is ideal for creating complex websites,
-integrating external tools, and building custom-built solutions.
-
-**Rector** helps successful and growing companies to get the most of the code
-they already have. Including upgrading to the latest Symfony LTS. They deliver
-automated refactoring, reduce maintenance costs, speed up feature delivery, and
-transform legacy code into a strategic asset. They can handle the dirty work,
-so you can focus on the features.
+**Les-Tilleuls.coop** is a team of 70+ Symfony experts who can help you design, develop and
+fix your projects. They provide a wide range of professional services including development,
+consulting, coaching, training and audits. They also are highly skilled in JS, Go and DevOps.
+They are a worker cooperative!
 
 Help Symfony by [sponsoring][28] its development!
 
@@ -96,5 +89,4 @@ and supported by [Symfony contributors][19].
 [26]: https://symfony.com/book
 [27]: https://symfony.com/backers
 [28]: https://symfony.com/sponsor
-[29]: https://sulu.io
-[30]: https://getrector.com
+[29]: https://les-tilleuls.coop