Problems with sbt-projectmatrix - upload artifact should be more granular

[ghostbuster91]

I am trying to port difflicious to use sbt-projectmatrix.

However the build fails at the uploadArtifacts stage:

Run tar cf targets.tar modules/weaver/target/jvm-2.13 modules/scalatest/target/jvm-2.13 modules/benchmarks/target/jvm-2.13 target docs/target/jvm-2.13 modules/core/target/jvm-3 modules/munit/target/jvm-3 modules/scalatest/target/jvm-3 modules/weaver/target/jvm-3 modules/benchmarks/target/jvm-3 modules/cats/target/jvm-3 modules/munit/target/jvm-2.13 modules/cats/target/jvm-2.13 modules/core/target/jvm-2.13 modules/coretest/target/jvm-3 modules/coretest/target/jvm-2.13 project/target
tar: modules/core/target/jvm-3: Cannot stat: No such file or directory
tar: modules/munit/target/jvm-3: Cannot stat: No such file or directory
tar: modules/scalatest/target/jvm-3: Cannot stat: No such file or directory
tar: modules/weaver/target/jvm-3: Cannot stat: No such file or directory
tar: modules/benchmarks/target/jvm-3: Cannot stat: No such file or directory
tar: modules/cats/target/jvm-3: Cannot stat: No such file or directory
tar: modules/coretest/target/jvm-3: Cannot stat: No such file or directory
tar: Exiting with failure status due to previous errors
Error: Process completed with exit code 2.

This is because directories for jvm-3 do not exist when we are building for jvm-2.13

Link to failed build

I saw #9 but the mentioned workaround doesn't make sense in our case.

I guess this could be solved by overriding githubWorkflowGeneratedUploadSteps but the readme seems to discourage it and having a better support for sbt-projectmatrix seems like a good improvement.