2020-06-02, Version 10.21.0 'Dubnium' (LTS)

This is a security release.

Vulnerabilities fixed:

- CVE-2020-8174: napi_get_value_string_*() allows various kinds of
                 memory corruption (High).
- CVE-2020-10531: ICU-20958 Prevent SEGV_MAPERR in append (High).
- CVE-2020-11080: HTTP/2 Large Settings Frame DoS (Low).

PR-URL: https://github.com/nodejs-private/node-private/pull/211