Update sponsor information with Stytch (#935)

- Remove clerk-dark.svg and clerk-light.svg from sponsor folder
- Add stytch-dark.svg and stytch-light.svg to sponsor folder
- Update README.md to reference Stytch

Author: howard-stytch

README.md

@@ -6,17 +6,17 @@
 
 ---
 <div align="center">
-  <a href="https://clerk.com">
+  <a href="https://stytch.com">
     <picture>
-      <source width="200px" media="(prefers-color-scheme: dark)" srcset="./sponsor/clerk-light.svg">
-      <source width="200px" media="(prefers-color-scheme: light)" srcset="./sponsor/clerk-dark.svg">
-      <img width="200px" src="./sponsor/clerk-dark.svg" />
+      <source width="200px" media="(prefers-color-scheme: dark)" srcset="./sponsor/stytch-light.svg">
+      <source width="200px" media="(prefers-color-scheme: light)" srcset="./sponsor/stytch-dark.svg">
+      <img width="200px" src="./sponsor/stytch-dark.svg" />
     </picture>
   </a>
-   <p align="center">Clerk is a complete suite of embeddable UIs, flexible APIs, and admin dashboards to authenticate and manage your users.</p>
    <p align="center">
-      <a href="https://go.clerk.com/198WZf0">
-        <b>Add authentication in 7 minutes 👉</b>
+      <a href="https://stytch.com/?utm_source=oss-sponsorship&utm_medium=paid_sponsorship&utm_campaign=ironsession">
+        <b>The identity platform for humans & AI agents</b><br/>
+        One integration for authentication, authorization, and security
       </a>
    </p>
 </div>