Update dehydrated and switch to ACMEv2

This makes everything work with Let's Encrypt again, and
allows wildcard certificates to be obtained.

csmith/docker-letsencrypt-lexicon#5
csmith/docker-letsencrypt-lexicon#6

config

@@ -6,8 +6,8 @@ CONTACT_EMAIL=$EMAIL
 KEY_ALGO=${ALGORITHM:-secp384r1}
 
 if [ -z ${STAGING+-} ]; then
-  CA="https://acme-v01.api.letsencrypt.org/directory"
+  CA="https://acme-v02.api.letsencrypt.org/directory"
 else
-  CA="https://acme-staging.api.letsencrypt.org/directory"
+  CA="https://acme-staging-v02.api.letsencrypt.org/directory"
 fi