Net::SSH dependency prevents using HMAC SHA2 family

Please update Net::SSH dependency to version 2.5.2

The current version of Chef depends on Net::SSH 2.2.2 which only supports
limited HMAC algorithms for transport (MD5 and SHA1 family). For certain
clients, we require newer algorithms (HMAC SHA2 family), which are
supported in Net-SSH 2.5.2. Connecting to nodes, which have transport
HMAC limited to these algorithms is currently not possible.

Reference for available HMAC algorithms in Net::SSH:
net-ssh-2.2.2/lib/net/ssh/transport/hmac.rb
net-ssh-2.5.2/lib/net/ssh/transport/hmac.rb