Correct return type of contracted_product

[ovanvincq]

For some reason, I use MultiValue with Unitful.jl and the behavior of the dot function has been modified with Gridap v0.20. Indeed this version returns an error because the return type of dot(a,b) is assumed to be identical to that of a or b, which is incorrect.

Example:

using Gridap, Unitful
v=VectorValue(1.0u"m",1.0u"m")
dot(v,v)

returns

• With v0.19: 2.0 m^2
• With v0.20: ERROR: DimensionError: m and 2.0 m^2 are not dimensionally compatible.

This PR restores the behavior of version 0.19.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 88.69%. Comparing base (62586b6) to head (7e7a2bd).
⚠️ Report is 3 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1270   +/-   ##
=======================================
  Coverage   88.69%   88.69%           
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  Files         226      226           
  Lines       29244    29244           
=======================================
  Hits        25939    25939           
  Misses       3305     3305           

Flag	Coverage Δ
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extensions	5.24% <21.42%> (ø)
unit-adaptivity	37.41% <28.57%> (ø)
unit-basics	13.82% <100.00%> (ø)
unit-celldata	21.43% <28.57%> (ø)
unit-fespaces-1	32.75% <28.57%> (ø)
unit-fespaces-2	39.28% <28.57%> (ø)
unit-fields	17.74% <28.57%> (ø)
unit-geometry	29.26% <28.57%> (ø)
unit-multifield	31.34% <28.57%> (ø)
unit-odes	29.18% <28.57%> (ø)
unit-referencefes	34.76% <42.85%> (ø)
unit-visualization	12.12% <28.57%> (ø)

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[JordiManyer]

Hi @ovanvincq thank you for the fix. Can we use Base.promote_op(*, Ta,Tb) instead?

[JordiManyer]

@Antoinemarteau can you check this does not appear anywhere else in your changes?

[ovanvincq]

@JordiManyer ok, I now use Base.promote_op(*, Ta,Tb) and I made the same modification in other product functions (in case of a 0-dimensional MultiValue).

[JordiManyer]

@ovanvincq Thank you again. Merged!