mailman: change lookup tables in main.cf to lmdb:

Arch's postfix 3.9.0-1 package removes support for BDB hash: and btree:
database types, and switches the default to LMDB. [1]

[1] archlinux/packaging/packages/postfix@2ebb2274

roles/mailman/templates/main.cf.j2

@@ -45,10 +45,10 @@ smtpd_reject_footer = For assistance contact <postmaster@archlinux.org>. Please
 smtpd_milters = inet:localhost:11332
 non_smtpd_milters = $smtpd_milters
 
-alias_maps = hash:/etc/postfix/aliases
-local_recipient_maps = hash:/var/lib/mailman/data/postfix_lmtp $alias_maps
+alias_maps = lmdb:/etc/postfix/aliases
+local_recipient_maps = lmdb:/var/lib/mailman/data/postfix_lmtp $alias_maps
 alias_database = $alias_maps
-transport_maps = hash:/var/lib/mailman/data/postfix_lmtp
+transport_maps = lmdb:/var/lib/mailman/data/postfix_lmtp
 
 milter_header_checks = pcre:/etc/postfix/milter_header_checks