Address PR comment

package.json

@@ -55,7 +55,6 @@
     "typescript": "^3.6.4"
   },
   "dependencies": {
-    "async-mutex": "^0.1.4",
     "bcrypto": "^4.2.3",
     "bn.js": "^5.0.0",
     "buffer": "^5.4.3",

src/keycache.ts

@@ -1,4 +1,3 @@
-import {Mutex} from 'async-mutex';
 import {PeerId} from "./@types/libp2p";
 import {bytes, bytes32} from "./@types/basic";
 
@@ -6,32 +5,14 @@ import {bytes, bytes32} from "./@types/basic";
  * Storage for static keys of previously connected peers.
  */
 class Keycache {
-  private mutex: Mutex;
   private storage = new Map<bytes, bytes32>();
 
-  constructor() {
-    this.mutex = new Mutex();
-  }
-
   public async store(peerId: PeerId, key: bytes32): Promise<void> {
-    const release = await this.mutex.acquire();
-    try {
-      this.storage.set(peerId.id, key);
-    } finally {
-      release();
-    }
+    this.storage.set(peerId.id, key);
   }
 
   public async load(peerId: PeerId): Promise<bytes32|null> {
-    const release = await this.mutex.acquire();
-    let key;
-    try {
-      key = this.storage.get(peerId.id) || null;
-    } finally {
-      release();
-    }
-
-    return key;
+    return this.storage.get(peerId.id) || null;
   }
 
   public resetStorage(): void {

yarn.lock

@@ -1086,11 +1086,6 @@ async-each@^1.0.1:
   resolved "https://registry.yarnpkg.com/async-each/-/async-each-1.0.3.tgz#b727dbf87d7651602f06f4d4ac387f47d91b0cbf"
   integrity sha512-z/WhQ5FPySLdvREByI2vZiTWwCnF0moMJ1hK9YQwDTHKh6I7/uSckMetoRGb5UBZPC1z0jlw+n/XCgjeH7y1AQ==
 
-async-mutex@^0.1.4:
-  version "0.1.4"
-  resolved "https://registry.yarnpkg.com/async-mutex/-/async-mutex-0.1.4.tgz#a47d1eebf584f7dcdd760e3642dc2c58613bef5c"
-  integrity sha512-zVWTmAnxxHaeB2B1te84oecI8zTDJ/8G49aVBblRX6be0oq6pAybNcUSxwfgVOmOjSCvN4aYZAqwtyNI8e1YGw==
-
 atob@^2.1.1:
   version "2.1.2"
   resolved "https://registry.yarnpkg.com/atob/-/atob-2.1.2.tgz#6d9517eb9e030d2436666651e86bd9f6f13533c9"