chore: add socket.io-parser to peerDependencies

This should (at least in theory) fix sync issues for the
`socket.io-adapter` package, which is imported by both the `socket.io`
and `@socket.io/redis-adapter` packages:

- `[email protected]` should resolve `socket.io-adapter@~2.4.0`
- `[email protected]` should resolve `socket.io-adapter@~2.5.0`

Related:

- 7aecf01
- #487

Author: darrachequesne

package-lock.json

@@ -25,9 +25,11 @@
   "dependencies": {
     "debug": "~4.3.1",
     "notepack.io": "~3.0.1",
-    "socket.io-adapter": "~2.4.0",
     "uid2": "1.0.0"
   },
+  "peerDependencies": {
+    "socket.io-adapter": "^2.4.0"
+  },
   "devDependencies": {
     "@types/expect.js": "^0.3.29",
     "@types/mocha": "^8.2.1",