Log Message:
security/ruby-sshkit: update to 1.20.0

Update ruby-sshkit package to 1.20.0.

## [1.20.0][] (2019-08-03)

  * [#468](https://github.com/capistrano/sshkit/pull/468): Make `upload!` take a \ 
`:verbosity` option like `exec` does - [@grosser](https://github.com/grosser)

## [1.19.1][] (2019-07-02)

  * [#465](https://github.com/capistrano/sshkit/pull/456): Fix a regression in \ 
1.19.0 that prevented `~` from being used in Capistrano paths, e.g. \ 
`:deploy_to`, etc. - [@grosser](https://github.com/grosser)

## [1.19.0][] (2019-06-30)

  * [#455](https://github.com/capistrano/sshkit/pull/455): Ensure UUID of \ 
commands are stable in logging - [@lazyatom](https://github.com/lazyatom)
  * [#453](https://github.com/capistrano/sshkit/pull/453): `as` and `within` now \ 
properly escape their user/group/path arguments, and the command nested within \ 
an `as` block is now properly escaped before passing to `sh -c`. In the unlikely \ 
case that you were manually escaping commands passed to SSHKit as a workaround, \ 
you will no longer need to do this. See \ 
[#458](https://github.com/capistrano/sshkit/issues/458) for examples of what has \ 
been fixed. - [@grosser](https://github.com/grosser)
  * [#460](https://github.com/capistrano/sshkit/pull/460): Handle IPv6 addresses \ 
without port - [@will-in-wi](https://github.com/will-in-wi)

## [1.18.2][] (2019-02-03)

  * [#448](https://github.com/capistrano/sshkit/pull/448): Fix misbehaving \ 
connection eviction loop when disabling connection pooling - [Sebastian \ 
Cohnen](https://github.com/tisba)

## [1.18.1][] (2019-01-26)

  * [#447](https://github.com/capistrano/sshkit/pull/447): Fix broken thread \ 
safety by widening critical section - [Takumasa \ 
Ochi](https://github.com/aeroastro)