Update to MOI v0.9

[blegat]

No description provided.

[coveralls]

Coverage increased (+0.7%) to 84.459% when pulling a84b55f on bl/moiv0.9 into c83bfe9 on master.

[codecov-io]

Codecov Report

Merging #28 into master will increase coverage by 0.59%.
The diff coverage is 73.33%.

@@            Coverage Diff             @@
##           master      #28      +/-   ##
==========================================
+ Coverage   86.51%   87.11%   +0.59%     
==========================================
  Files           6        6              
  Lines         356      357       +1     
==========================================
+ Hits          308      311       +3     
+ Misses         48       46       -2

Impacted Files	Coverage Δ
src/constraint.jl	95.65% <100%> (ø)	⬆️
src/SemidefiniteOptInterface.jl	86.51% <66.66%> (-1.99%)	⬇️
src/mock.jl	79.62% <66.66%> (+3.48%)	⬆️
src/variable.jl	87.87% <80%> (ø)	⬆️

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