Fix kron product on sum spaces

[mzaffalon]

Fix JuliaApproximation/ApproxFun.jl#929.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 74.30%. Comparing base (023b1a4) to head (6603ad2).
Report is 4 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #640      +/-   ##
==========================================
- Coverage   75.20%   74.30%   -0.90%     
==========================================
  Files          79       79              
  Lines        8445     8446       +1     
==========================================
- Hits         6351     6276      -75     
- Misses       2094     2170      +76     

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[jishnub]

Thanks! Could you also bump the patch version?

[mzaffalon]

You mean Project.toml?

[jishnub]

Yes, please update the version to 0.9.26. I will merge and tag a release

[mzaffalon]

Thank you!

Would you merge also JuliaApproximation/ApproxFunFourier.jl#117 or would you like more tests?

[jishnub]

I think that's fine. I'll merge that after backporting this to the v0.8 branch.