Update outdated cargo dependencies

[haerdib]

Our current cargo dependencies are partially quite outdated. If we're refactoring anyway, I think it would make sense to update these dependencies.
Some examples:

• from worker toml
  
• from enclave toml
  

[murerfel]

This is related to #189 - I was able to update some of them (like multihash). But for others like aes and ofb, we are version locked, due to other dependencies atm.