[15.0] auto_backup old cryptography version requirement

[Ma1pa]

Is your feature request related to a problem?
The request is related to a dependency on a specific outdated version of a python library.
In this case with cryptography version 2.6.1

Describe the solution you'd like
Remove the restriction forcing the user to use cryptography 2.6.1 on auto_backup on Odoo 15.0, just like on 16.0

Describe alternatives you've considered
If there is any requirement to use from cryptography 2.6.1, set the requirements to require at least that version and not force the users to stay on an outdated version.

Additional context
Cryptography version 2.6.1 is from february 2019 and since there have been multiple updates to the library.
Many modules also require either a posterior version or another library that requires a posterior version of cryptography.
Also, the module for Odoo 16.0 only requires the library Cryptography, no specific version; which shows that there is not much reason to only allow for such version.