Old version of https-proxy-agent used

Summary

axios is currently using version 5.0.1 of https-proxy-agent which was released 4 years ago and agent-base version 6 which was released 6 years ago. The most recent versions are 9.1.0 for https-proxy-agent (today 15 days old) and 9.0.0 for agent-base (3 months old).

Background

With this PR, the usage of https-proxy-agent was introduced. The version that was added is ^5.0.1. While this is not an issue in itself, some code scanners will flag this as outdated considering that this version is 4 years old. The package is actively worked on and is currently available in version 9.1.0. Additionally, using https-proxy-agent in version 5 introduces the usage of agent-base in version 6 which is 6 years old (the most current version is 9.0.0 which was released 3 months ago).

I'm opening this issue as non-maintainers are not allowed to open PRs to update dependencies.