set method doesn't include user set timestamp if update set() is supposed to update the record with the key if it already exists. It does update the value marshalled data blob. However it doesn't update the timestamp column for rdbms tables if provided. This change updates the x_time column with the provided __timestamp or preserves the original timestamp.

# human timezones
pytz
# indexer
Whoosh
# extra database support
psycopg2
mysqlclient
# encryption
gpg
# java web tokens
PyJWT
# extra HTTP compression methods
Brotli
zstd