CI: remove sponsors generation (moved to website)

Signed-off-by: Stephen Gutekanst <stephen@hexops.com>

.github/workflows/sponsors.yml

@@ -1,35 +0,0 @@
-name: Generate Sponsors README
-on:
-  push:
-    branches:
-      - main
-jobs:
-  deploy:
-    runs-on: ubuntu-latest
-    steps:
-      - name: Checkout
-        uses: actions/checkout@v2
-
-      - name: Generate Sponsors (bronze) 💖
-        uses: slimsag/github-sponsors-readme-action@dev
-        with:
-          token: ${{ secrets.SLIMSAG_SPONSORS_PAT }}
-          file: 'README.md'
-          maximum: 600 # cents
-          marker: 'bronze'
-
-      - name: Generate Sponsors (silver) 💖
-        uses: slimsag/github-sponsors-readme-action@dev
-        with:
-          token: ${{ secrets.SLIMSAG_SPONSORS_PAT }}
-          file: 'README.md'
-          minimum: 2500 # cents
-          maximum: 2600 # cents
-          marker: 'silver'
-
-      - name: Push changes to GitHub
-        uses: JamesIves/github-pages-deploy-action@4.1.1
-        with:
-          branch: main
-          folder: '.'
-          commit-message: 'README: regenerate sponsors section'