sysutils/autorestic: Update to 1.8.3

ChangeLog: https://github.com/cupcakearmy/autorestic/releases/tag/v1.8.3

• Bump restic/restic from 0.16.4 to 0.17.0.
• install.sh: FreeBSD amd64.
• Add option to crash autorestic when key is missing instead of generating a new key.
• When reading backend config values from environment variables treat all special characters in backend name as _.

PR: 254276