Bump cryptography from 2.8 to 3.2 in /desktop/core
Bumps [cryptography](https://github.com/pyca/cryptography) from 2.8 to 3.2.
- [Release notes](https://github.com/pyca/cryptography/releases)
- [Changelog](https://github.com/pyca/cryptography/blob/master/CHANGELOG.rst)
- [Commits](https://github.com/pyca/cryptography/compare/2.8...3.2)
Signed-off-by: dependabot[bot] <support@github.com>