Drop support for OpenSSL 1.0.2. It has reached upstream EOL in 2019-12.

Most distributions that shipped with OpenSSL 1.0.2 have also reached
EOL, or provide a newer version in the package repository:

 - RHEL 7 (EOL 2024-06)
 - Ubuntu 16.04 LTS (EOL 2021-04)
 - Amazon Linux 2 (EOL 2026-06, but OpenSSL 1.1.1 can be installed via
   the openssl11{,-devel} package)

https://github.com/ruby/openssl/commit/38ec6fd50e