Saleor CSRF bypass in refreshToken mutation

Saleor is an e-commerce platform. Starting in version 3.10.0 and prior to versions 3.14.64, 3.15.39, 3.16.39, 3.17.35, 3.18.31, and 3.19.19, an attacker may bypass cross-set request forgery (CSRF) validation when calling refresh token mutation with empty string. When a user provides an empty string in `refreshToken` mutation, while the token persists in `JWT_REFRESH_TOKEN_COOKIE_NAME` cookie, application omits validation against CSRF token and returns valid access token. Versions 3.14.64, 3.15.39, 3.16.39, 3.17.35, 3.18.31, and 3.19.19 contain a patch for the issue. As a workaround, one may replace `saleor.graphql.account.mutations.authentication.refresh_token.py.get_refresh_token`. This will fix the issue, but be aware, that it returns `JWT_MISSING_TOKEN` instead of `JWT_INVALID_TOKEN`.