Remove Tuple sponsorship banner - sponsorship has ended

Author: horenmar

README.md

@@ -1,16 +1,5 @@
 <a id="top"></a>
-
-<table width="100%">
-  <tr>
-    <td align="center" width="50%"><img src="/data/artwork/catch2-logo-full-with-background.svg" width="100%"></td>
-    <td align="center" width="50%">
-      <figure>
-        <figcaption>Special thanks to:</figcaption>
-        <a href="https://tuple.app/catch2"><img src="/data/sponsors/github_repo_sponsorship.png" width="100%"></a>
-      </figure>
-    </td>
-  </tr>
-</table>
+![Catch2 logo](data/artwork/catch2-logo-full-with-background.svg)
 
 [![Github Releases](https://img.shields.io/github/release/catchorg/catch2.svg)](https://github.com/catchorg/catch2/releases)
 [![Linux build status](https://github.com/catchorg/Catch2/actions/workflows/linux-simple-builds.yml/badge.svg)](https://github.com/catchorg/Catch2/actions/workflows/linux-simple-builds.yml)