package/ruby: security bump to version 3.0.2

Fixes the following security issues:

- CVE-2021-31810: Trusting FTP PASV responses vulnerability in Net::FTP
- CVE-2021-32066: A StartTLS stripping vulnerability in Net::IMAP
- CVE-2021-31799: A command injection vulnerability in RDoc

For more details, see the announcement:
https://www.ruby-lang.org/en/news/2021/07/07/ruby-3-0-2-released/



Signed-off-by: Peter Korsgaard <peter@korsgaard.com>