Update README

I was unable to make the sponsors action to work with the new branch
protection rule. So I'm removing the sponsors section for now until
I can properly set it up again.

.github/workflows/sponsors.yml

@@ -1,24 +0,0 @@
----
-name: Generate Sponsors README
-on:
-  workflow_dispatch:
-  schedule:
-    - cron: 0 15 * * 6
-jobs:
-  deploy:
-    runs-on: ubuntu-latest
-    steps:
-      - name: Checkout 🛎️
-        uses: actions/checkout@v5
-
-      - name: Generate Sponsors 💖
-        uses: JamesIves/github-sponsors-readme-action@2fd9142e765f755780202122261dc85e78459405 # v1
-        with:
-          token: ${{ secrets.SPONSORS_TOKEN }}
-          file: 'README.md'
-
-      - name: Deploy to GitHub Pages 🚀
-        uses: JamesIves/github-pages-deploy-action@d92aa235d04922e8f08b40ce78cc5442fcfbfa2f # v4
-        with:
-          branch: master
-          folder: '.'