move to `--auth PLAIN` from `--auth LOGIN`

because LOGIN is deprecated (according to swaks documentation).

test/tests/parallel/set3/mta/privacy.bats

@@ -26,7 +26,7 @@ function teardown_file() { _default_teardown ; }
 # this test covers https://github.com/docker-mailserver/docker-mailserver/issues/681
 @test "(Postfix) remove privacy details of the sender" {
   _send_email \
-    --port 587 -tls --auth LOGIN \
+    --port 587 -tls --auth PLAIN \
     --auth-user user1@localhost.localdomain \
     --auth-password mypassword \
     --data 'privacy'

test/tests/serial/mail_with_imap.bats

@@ -31,8 +31,8 @@ function teardown_file() { _default_teardown ; }
 }
 
 @test '(SASLauthd) RIMAP SMTP authentication works' {
-    --auth LOGIN \
   _send_email_unchecked \
+    --auth PLAIN \
     --auth-user user1@localhost.localdomain \
     --auth-password mypassword \
     --quit-after AUTH
@@ -41,7 +41,7 @@ function teardown_file() { _default_teardown ; }
 
   _send_email \
     --port 465 \
-    --auth LOGIN \
+    --auth PLAIN \
     --auth-user user1@localhost.localdomain \
     --auth-password mypassword \
     --quit-after AUTH
@@ -49,7 +49,7 @@ function teardown_file() { _default_teardown ; }
 
   _send_email \
     --port 587 \
-    --auth LOGIN \
+    --auth PLAIN \
     --auth-user user1@localhost.localdomain \
     --auth-password mypassword \
     --quit-after AUTH

test/tests/serial/mail_with_ldap.bats

@@ -326,8 +326,8 @@ function teardown() {
 @test "spoofing (with LDAP): rejects sender forging" {
   _wait_for_smtp_port_in_container_to_respond dms-test_ldap
 
-    --port 465 -tlsc --auth LOGIN \
   _send_email_unchecked \
+    --port 465 -tlsc --auth PLAIN \
     --auth-user some.user@localhost.localdomain \
     --auth-password secret \
     --ehlo mail \
@@ -339,7 +339,7 @@ function teardown() {
 
 @test "spoofing (with LDAP): accepts sending as alias" {
   _send_email \
-    --port 465 -tlsc --auth LOGIN \
+    --port 465 -tlsc --auth PLAIN \
     --auth-user some.user@localhost.localdomain \
     --auth-password secret \
     --ehlo mail \
@@ -354,8 +354,8 @@ function teardown() {
   # Template used has invalid AUTH: https://github.com/docker-mailserver/docker-mailserver/pull/3006#discussion_r1073321432
   skip 'TODO: This test seems to have been broken from the start (?)'
 
-    --port 465 -tlsc --auth LOGIN \
   _send_email_unchecked \
+    --port 465 -tlsc --auth PLAIN \
     --auth-user some.user.email@localhost.localdomain \
     --auth-password secret \
     --ehlo mail \
@@ -367,8 +367,8 @@ function teardown() {
 }
 
 @test "saslauthd: ldap smtp authentication" {
-    --auth LOGIN \
   _send_email_unchecked \
+    --auth PLAIN \
     --auth-user some.user@localhost.localdomain \
     --auth-password wrongpassword \
     --quit-after AUTH
@@ -385,7 +385,7 @@ function teardown() {
 
   _send_email \
     --port 587 -tls \
-    --auth LOGIN \
+    --auth PLAIN \
     --auth-user some.user@localhost.localdomain \
     --auth-password secret \
     --quit-after AUTH

test/tests/serial/tests.bats

@@ -293,8 +293,8 @@ EOF
 
   # An authenticated user cannot use an envelope sender (MAIL FROM)
   # address they do not own according to `main.cf:smtpd_sender_login_maps` lookup
-    --port 465 -tlsc --auth LOGIN \
   _send_email_unchecked \
+    --port 465 -tlsc --auth PLAIN \
     --auth-user added@localhost.localdomain \
     --auth-password mypassword \
     --ehlo mail \
@@ -310,7 +310,7 @@ EOF
   # to each table. Address is authorized when a result that maps to
   # the DMS account is returned.
   _send_email \
-    --port 465 -tlsc --auth LOGIN \
+    --port 465 -tlsc --auth PLAIN \
     --auth-user user1@localhost.localdomain \
     --auth-password mypassword \
     --ehlo mail \