I don't think either of those are supported any more. Even 3.9 is listed as deprecated.
>With the release of the all-new Spring Tools 4, the Spring Tool Suite 3 got deprecated and is no longer under active development.
https://github.com/spring-projects/toolsuite-distribution/wiki/Spring-Tool-Suite-3
The most recent releases of 3.9 also indicates:
>This is a minor bugfix and maintenance release that we ship to our existing STS3 users beyond the announced maintenance lifespan for your convenience.
https://docs.spring.io/sts/nan/v3915/NewAndNoteworthy.html
so while 3.9 is still seeing some updates, those are not guaranteed and could end at any point.
In short, you should strongly look at upgrading to STS4 as soon as possible.