[NOTICE] Flink 1.12.3 artifacts for Scala 2.12 were built against Scala 2.11

[Chesnay Schepler]

To all Scala 2.12 users,

Due to a mistake during the release process of Flink 1.12.3 jars
intended to be built against Scala 2.12 were actually built against
Scala 2.11 .
This affects all jars published to maven central; the convenience
binaries are not affected.

Scala 2.12 users are advised to not upgrade to Flink 1.12.3, and instead
wait for 1.12.4, which we will try to release as soon as possible.

Regards,
Chesnay