[13u notice]: jdk 13.0.4 rampdown started

[Yuri Nesterenko]

Hi all,

the last build tag for jdk 13.0.4 was set. The last merge from jdk13u-dev to jdk13u
will be performed shortly, and jdk13u-dev will be reopened for changes targeted to 13.0.5.

Critical changes, if any, must be requested with jdk13u-critial-request and pushed to the
master jdk13u directly.

There will be soon a separate notice about jdk13u-dev reopening.

Thanks,
--yan