Update dependency phpseclib/phpseclib

[boksie]

I cannot use the plugin in my project because of the dependency on phpseclib/phpseclib:^2.0.
Can the plugin be updated so the dependency also supports phpseclib/phpseclib:^3.0?

[lruozzi9]

Hi, you cannot use version 2 probably because of the vulnerability contained in v2 of that library: GHSA-jpr7-q523-hx25. ASAP I can try to provide a PR to fix it.