Fix mysql 8 auth plugin

.travis.yml

@@ -63,9 +63,9 @@ env:
   - config: postgres-old.yml
 
 
-  # mysql 8 (not supported, test fail)
-  # - config: mysql.yml
-  #   MYSQL_VERSION: 8
+  # mysql 8
+  - config: mysql.yml
+    MYSQL_VERSION: 8
 
   # mysql 5
   - config: mysql.yml

tests/mysql.yml

@@ -21,6 +21,7 @@ services:
   onlyoffice-mysql:
     container_name: onlyoffice-mysql
     image: mysql:${MYSQL_VERSION:-5.7}
+    command: --default-authentication-plugin=mysql_native_password
     environment:
       - MYSQL_DATABASE=${MYSQL_DATABASE:-onlyoffice}
       - MYSQL_USER=${MYSQL_USER:-onlyoffice}