fix: --dry-run mode in sanctuary

Closes #34 (closed)

Changes in this MR:

1. `--dry-run` mode is now explicitly "verbose". No need to add `--verbose` option.

   before:

   $ sanctuary sync --dry-run
   # no output

   after:

   $ sanctuary sync --dry-run
   [info     ] Enabling dry run. Secrets will not be changed.
   [info     ] Processing secret              secret_name=secretname
   [info     ] Using application default Google credentials.
   [info     ] Ensuring that secret exists and is ready for update. secret=SecretSpec(google_secret=GoogleSecret(project='project', name='secret', version='latest', destroy_previous_versions=False), op_cli_item=None, op_cli_document=None)
   [info     ] Updating secret                from_secret=SecretSpec(google_secret=None, op_cli_item=OnePasswordCLIItem(item_id='someidhere', fields=['secret_field'], field=None, use_field_labels=True), op_cli_document=None) to_secret=SecretSpec(google_secret=GoogleSecret(project='project', name='secret', version='latest', destroy_previous_versions=False), op_cli_item=None, op_cli_document=None)

2. Now even with --dry-run the script checks if secret exists on GCP side.

   before:

   $ sanctuary sync --dry-run
   [info     ] Enabling dry run. Secrets will not be changed.
   [info     ] Processing secret              secret_name=secretname
   [info     ] Using application default Google credentials.
   [info     ] Ensuring that secret exists and is ready for update. secret=SecretSpec(google_secret=GoogleSecret(project='project', name='secret_not_exists', version='latest', destroy_previous_versions=False), op_cli_item=None, op_cli_document=None)
   [info     ] Updating secret                from_secret=SecretSpec(google_secret=None, op_cli_item=OnePasswordCLIItem(item_id='someidhere', fields=['secret_field'], field=None, use_field_labels=True), op_cli_document=None) to_secret=SecretSpec(google_secret=GoogleSecret(project='project', name='secret', version='latest', destroy_previous_versions=False), op_cli_item=None, op_cli_document=None)

   after:

   $ sanctuary sync --dry-run
   [info     ] Enabling dry run. Secrets will not be changed.
   [info     ] Processing secret              secret_name=development
   [info     ] Using application default Google credentials.
   [info     ] Ensuring that secret exists and is ready for update. secret=SecretSpec(google_secret=GoogleSecret(project='project', name='secret_not_exists', version='latest', destroy_previous_versions=False), op_cli_item=None, op_cli_document=None)
   [error    ] Error processing secret.       error_message=Google secrets must be created before being set. secret_name=development