Old pingcap image versions.

[dveeden]

The pingcap/tidb:latest image points to an old version. pingcap/tidb:v5.3.0 is much more recent. The same is true for many (if not all) of the pingcap images.

I would suggest to:

• Change the tag from latest to v5.3.0 (or other explicit versions for TiSpark, TiVision, etc) in the yaml files
• Update or remove the latest tag

[dveeden]

cc @zhouqiang-cl

[dveeden]

cc @yahonda