fix lasso tests on GPU

[mtar]

Description

Fixes the tests in test_lasso.py such that it completes on GPU.

Issue/s resolved: #462

Changes proposed:

• adding device parameters
• numpy() -> cpu().numpy()

Type of change

• Bug fix (non-breaking change which fixes an issue)

Does this change modify the behaviour of other functions? If so, which?

no

[codecov]

Codecov Report

Merging #463 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #463      +/-   ##
==========================================
+ Coverage   96.68%   96.69%   +<.01%     
==========================================
  Files          57       57              
  Lines       12134    12147      +13     
==========================================
+ Hits        11732    11745      +13     
  Misses        402      402

Impacted Files	Coverage Δ
heat/core/tests/test_manipulations.py	99.26% <100%> (ø)	⬆️
heat/core/manipulations.py	99.2% <100%> (ø)	⬆️

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[coquelin77]

please update changelog.md with the change