Error assembly System.Memory in unity 2020.3

[Thomasdfoz]

To fix the error, just edit itisnajim.SocketIOUnity.asmdef and add this library

{
    "name": "SocketIOUnityAssembly",
    "rootNamespace": "",
    "references": [],
    "includePlatforms": [],
    "excludePlatforms": [],
    "allowUnsafeCode": false,
    "overrideReferences": true,
    "precompiledReferences": [
        "Microsoft.Bcl.AsyncInterfaces.dll",
        "Newtonsoft.Json.dll",
        "System.Reactive.dll",
        "System.Runtime.CompilerServices.Unsafe.dll",
        "System.Text.Json.dll",
        "System.Text.Encodings.Web.dll",
	"System.Memory.dll"

    ],
    "autoReferenced": true,
    "defineConstraints": [],
    "versionDefines": [],
    "noEngineReferences": false
}