Upgrade openssl to avoid a security vulnerability

[sehkone]

Dependabot reported a moderate vulnerability in openssl.. Need to release a new version using the recent version of openssl.

[sophie-cluml]

I think we do not need to urgently release a new giganto version just to resolve this openssl vulnerability, because openssl crate isn't really being used by giganto. I think this vulnerability alert will be handled when we release the next giganto version, by running cargo update as we are supposed to.

[kimhanbeom]

The issue has been resolved(#796), so I'll close it.