fix: override protobufjs to >=7.5.6 to resolve CVE (GHSA-jvwf-75h9-cwgg)

protobufjs <7.5.6 is vulnerable to process-wide denial of service
through unsafe option paths. The vulnerable version (7.4.0) was pulled
in transitively via @atproto/bsky -> etcd3 -> @grpc/proto-loader.

Added a pnpm override to force protobufjs >=7.5.6 (resolved to 8.2.0).

Author: MathurAditya724

package.json

@@ -34,5 +34,10 @@
     "*.{js,ts,cjs,mjs,json}": [
       "biome check --write --"
     ]
+  },
+  "pnpm": {
+    "overrides": {
+      "protobufjs": ">=7.5.6"
+    }
   }
 }