Base64 may not be URL safe

[Rohitrajak1807]

javascript_playground/sharding/index.js

Line 65 in bc01f3c

const hash = crypto.createHash("sha256").update(url).digest("base64")

@hnasr base64 encoding used in the URL shortener may have a '/' un the URL_ID, so using digest('base64url') is advised to avoid this.