VPN-4695: Force version downgrade for openssl and openssl-sys crates

[oskirby]

Description

Recently we have been failing to build the VPN client on Ubuntu/bionic due to a linker error between qtglean and libssl the offending symbols are X509_get0_authority_issuer and X509_get0_authority_serial. We have filed an upstream PR to fix the issue properly, but in order to get the 2.15.0 release building again, we may need to force a downgrade of the openssl and openssl-sys crates.

Note that this PR is only targeting the 2.15.0 release. I predict that we are either going to deprecate Ubuntu/bionic for 2.16.0, or the upstream project will release a fix.

Reference

Github issue #6772 (VPN-4695)

Checklist

• My code follows the style guidelines for this project
• I have not added any packages that contain high risk or unknown licenses (GPL, LGPL, MPL, etc. consult with DevOps if in question)
• I have performed a self review of my own code
• I have commented my code PARTICULARLY in hard to understand areas
• I have added thorough tests where needed