* Add support for POST-as-GET if GET fails with 405.
* Bumping ACME test container version to 1.4. This includes letsencrypt/pebble#162 and letsencrypt/pebble#168.
* Also use POST-as-GET for account data retrival.
This is not yet supported by any ACME server (see letsencrypt/pebble#171),
so we fall back to a regular empty update if a 'malformedRequest' error is
returned.
* Using newest ACME test container image.
Includes letsencrypt/pebble#171 and letsencrypt/pebble#172, which make Pebble behave closer to the current specs.
* Remove workaround for old Pebble version.
* Add changelog entry.
* First try POST-as-GET, then fall back to unauthenticated GET.
(cherry picked from commit 92d9569bc9)
