Add github labels actions integration for peepmatic

.github/subscribe-to-label.json

@@ -1,6 +1,6 @@
 {
   "bnjbvr": ["cranelift"],
-  "fitzgen": ["fuzzing"],
+  "fitzgen": ["fuzzing", "cranelift:area:peepmatic"],
   "peterhuene": ["wasmtime:api", "wasmtime:c-api"],
   "kubkon": ["wasi"]
 }