main/nodejs: security upgrade to 12.18.0
Node.js v12.18.0 was released to address three CVEs:
- CVE-2020-8172: TLS session reuse can lead to host certificate verification bypass (High).
- CVE-2020-11080: HTTP/2 Large Settings Frame DoS (Low).
- CVE-2020-8174: napi_get_value_string_*() allows various kinds of memory corruption (High).
See https://github.com/nodejs/node/blob/master/doc/changelogs/CHANGELOG_V12.md#12.18.0 and https://nodejs.org/en/blog/vulnerability/june-2020-security-releases/