Resolve Matrix bitmaps soundness advisory

Author: dhawal-ss

mesh/scripts/rust-dependency-policy.json

@@ -46,11 +46,19 @@
     "yanked"
   ],
   "expectedRawWarningCounts": {
-    "unmaintained": 22,
+    "unmaintained": 23,
     "unsound": 2,
     "yanked": 1
   },
   "shippingRuntimeWarnings": [
+    {
+      "kind": "unmaintained",
+      "id": "RUSTSEC-2026-0247",
+      "package": "bitmaps",
+      "version": "3.1.0",
+      "status": "reviewed-transitive-warning",
+      "remediation": "Remove when the Matrix SDK dependency chain migrates away from the archived bitmaps crate; keep bitmaps below the RUSTSEC-2025-0167 affected range until then."
+    },
     {
       "kind": "unmaintained",
       "id": "RUSTSEC-2025-0057",