Update settings.py

Django gives a system error on MariaDB on VARCHARs longer than 255 chars. This was a limitation in older versions of mysql.
Meaning: You cannot run Paperless-NGX on older version were this limitation were present, meaning Django plays it extremely safe by giving an error.
This fixes this problem.

src/paperless/settings.py

@@ -347,6 +347,11 @@ if os.getenv("PAPERLESS_DBHOST"):
     if os.getenv("PAPERLESS_DBENGINE") == "mariadb":
         engine = "django.db.backends.mysql"
         options = {"read_default_file": "/etc/mysql/my.cnf", "charset": "utf8mb4"}
+        #Silence Django erros on old MariaDB versions where VARCHAR were limited to 255 chars.
+        #https://docs.djangoproject.com/en/4.1/ref/checks/#database
+        #https://mariadb.com/kb/en/innodb-system-variables/#innodb_large_prefix
+        SILENCED_SYSTEM_CHECKS = ["mysql.W003"]
+
     else:  # Default to PostgresDB
         engine = "django.db.backends.postgresql_psycopg2"
         options = {"sslmode": os.getenv("PAPERLESS_DBSSLMODE", "prefer")}