Enable SymEngine for 0.4.4 see if it also passes

[utensil]

Don't merge, only a test. Related to #37 .

[codecov]

Codecov Report

Merging #149 into 0.4.4-release will increase coverage by 6.69%.
The diff coverage is n/a.

@@                Coverage Diff                @@
##           0.4.4-release     #149      +/-   ##
=================================================
+ Coverage          66.51%   73.21%   +6.69%     
=================================================
  Files                  8        8              
  Lines               4898     6275    +1377     
=================================================
+ Hits                3258     4594    +1336     
- Misses              1640     1681      +41

Impacted Files	Coverage Δ
galgebra/deprecated.py	100% <0%> (+1.53%)	⬆️
galgebra/ga.py	79.52% <0%> (+5.19%)	⬆️
galgebra/utils.py	71.87% <0%> (+5.2%)	⬆️
galgebra/lt.py	49.67% <0%> (+6.57%)	⬆️
galgebra/mv.py	72% <0%> (+10.38%)	⬆️
galgebra/metric.py	81.28% <0%> (+10.74%)	⬆️

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[isuruf]

If you do, from sympy import diff it'll use the sympy function regardless of the environment variable value. If you do from sympy.core.backend import diff, then diff will either be a sympy function or a symengine function depending on the environment variable.