Release v3.1.2-proton
This release is v3.1.2 with support for the following non-standardized features:
- Presistent symmetric keys draft-ietf-openpgp-persistent-symmetric-keys-00
- Automatic forwarding draft-wussler-openpgp-forwarding-00
- Post-quantum algorithms draft-ietf-openpgp-pqc
- Proton profiles