• #396: When a database command errors, display and log the error message instead of swallowing it.
• #501: Optionally error if a source directory does not exist via "source_directories_must_exist"
  option in borgmatic's location configuration.
• #576: Add support for "file://" paths within "repositories" option.
• #612: Define and use custom constants in borgmatic configuration files. See the documentation for
  more information:
  https://torsion.org/borgmatic/docs/how-to/make-per-application-backups/#constant-interpolation
• #618: Add support for BORG_FILES_CACHE_TTL environment variable via "borg_files_cache_ttl" option
  in borgmatic's storage configuration.
• #623: Fix confusing message when an error occurs running actions for a configuration file.
• #635: Add optional repository labels so you can select a repository via "--repository yourlabel"
  at the command-line. See the configuration reference for more information:
  https://torsion.org/borgmatic/docs/reference/configuration/
• #649: Add documentation on backing up a database running in a container:
  https://torsion.org/borgmatic/docs/how-to/backup-your-databases/#containers
• #655: Fix error when databases are configured and a source directory doesn't exist.
• Add code style plugins to enforce use of Python f-strings and prevent single-letter variables.
  To join in the pedantry, refresh your test environment with "tox --recreate".
• Rename scripts/run-full-dev-tests to scripts/run-end-to-end-dev-tests and make it run end-to-end
  tests only. Continue using tox to run unit and integration tests.