chore: add Renovate package rule to block Pillow >=12.0.0

Pillow 12.x is incompatible with fastembed which requires pillow<12.0.0.
Added package rule to prevent Renovate from updating Pillow to version 12+
and reverted pyproject.toml to use pillow<12.0.0.

Co-authored-by: Chris Coutinho <cbcoutinho@users.noreply.github.com>

renovate.json

@@ -4,5 +4,11 @@
     "config:best-practices",
     "mergeConfidence:all-badges"
   ],
-  "dependencyDashboard": true
+  "dependencyDashboard": true,
+  "packageRules": [
+    {
+      "matchPackageNames": ["pillow"],
+      "allowedVersions": "<12.0.0"
+    }
+  ]
 }