Feature: PGP Asymmetric Encryption (#456)

* feat: asym encryption

* tests

* docs

* refactor

* logs & errs

* comment

* Update docs/reference/index.md

use correct env var in example

Co-authored-by: Frederik Ring <frederik.ring@gmail.com>

* Update cmd/backup/encrypt_archive.go

use errwarp for initial error msg

Co-authored-by: Frederik Ring <frederik.ring@gmail.com>

* rm orphaned code in encryption functions

* inline readArmoredKeys

* naming -GPG_PUBLIC_KEYS- to GPG_PUBLIC_KEY_RING

* add eror handling for closing func

* use dynamically generated keys for testing

* rm explicit gpg-agent start

* rm unnecessary private_key export

* pass PASSPHRASE correctly to the decryption command

* capture defer errors

* log & err msg

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Co-authored-by: Frederik Ring <frederik.ring@gmail.com>

Add support for Azure storage access tiers (#452)

Bump shoutrrr to version 0.8 (#450)

Print stack trace when encountering unexpected panic (#406)

Allow authentication using connection string when targeting Azure Blo…

…b Storage (#383)

* Allow authentication using connection string when targeting Azure Blob Storage

* Bail on ambiguous configuration

Swarm mode check fails on non-standard Info responses (#376)

* Swarm mode check fails on non-standard Info responses

* Add unit test

* Remove balena tests, add note to docs

Lines from conf files that are comments should not be passed to shell…

….Expand (#374)

Allow backup to be run as non-root user

Conf files should expand env vars (#363)

Remove stray log statement (#359)