Remove artifacts from dependency links

[benjaoming]

Dependency links are not support in Pip 9, which is already released. But we haven't needed them since #5319 was solved.

• Removing this should ensure that ka-lite-static builds on Pip 9.
• Also added a make target sdist for installers.

[codecov-io]

Current coverage is 51.82% (diff: 100%)

Merging #5391 into develop will not change coverage

@@            develop      #5391   diff @@
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  Files           143        143          
  Lines          7491       7491          
  Methods           0          0          
  Messages          0          0          
  Branches          0          0          
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  Hits           3882       3882          
  Misses         3609       3609          
  Partials          0          0          

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[benjaoming]

This should be safe to merge - if it causes issues, they will show up during building of installers, however since Pip 9 is already out, it's also quite critical to get rid of this deprecated call.

[radinamatic]

Tested the pip install this morning, all's well! 👍