Update Sponsor information - Stytch (#960)

Author: howard-stytch

README.md

@@ -15,6 +15,26 @@ Passport-SAML has been tested to work with Onelogin, Okta, Shibboleth,
 [SimpleSAMLphp](http://simplesamlphp.org/) based Identity Providers, and with
 [Active Directory Federation Services](http://en.wikipedia.org/wiki/Active_Directory_Federation_Services).
 
+## Sponsors
+
+We gratefully acknowledge support from our sponsors:
+
+<div align="center">
+  <a href="https://stytch.com">
+    <picture>
+      <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">
+      <a href="https://stytch.com/?utm_source=oss-sponsorship&utm_medium=paid_sponsorship&utm_campaign=passportsaml">
+        <b>The identity platform for humans & AI agents</b><br/>
+        One integration for authentication, authorization, and security
+      </a>
+   </p>
+</div>
+
 ## Installation
 
 ```shell