v0.13.0 - "If at first you don't succeed"

This release fixes a bug in Vaultenv's retry behaviour.
The bug caused Vaultenv to crash immediately if it failed to retrieve
the mount information or a secret from the Vault server, while it was
supposed to retry fetching that information.

If Vaultenv fails to fetch the mount info or one or more secrets it will
now correctly retry fetching that information according to the
configured retry policy. This retry policy is (and was) configurable
with the options --retry-base-delay-milliseconds /
VAULTENV_RETRY_BASE_DELAY_MS and --retry-attempts /
VAULTENV_RETRY_ATTEMPTS.

Vaultenv will now also redact the used Vault token before outputting an
error message when a secret or the mount info cannot be fetched within
the retry period.