Fix jacobi integral where one order needs shifting

[jishnub]

After this,

julia> Integral(Jacobi(0,4))
IntegralWrapper : Jacobi(0,4) → Jacobi(0,4)
 0.0                 0.0                  …    ⋅                    ⋅
 0.3333333333333333  0.16666666666666666       ⋅                    ⋅
  ⋅                  0.21428571428571427       ⋅                    ⋅
  ⋅                   ⋅                        ⋅                    ⋅
  ⋅                   ⋅                        ⋅                    ⋅
  ⋅                   ⋅                   …    ⋅                    ⋅
  ⋅                   ⋅                        ⋅                    ⋅
  ⋅                   ⋅                        ⋅                    ⋅
  ⋅                   ⋅                      -0.03557312252964427   ⋅
  ⋅                   ⋅                       0.015151515151515143  ⋱
  ⋅                   ⋅                   …    ⋱                    ⋱

[codecov]

Codecov Report

Patch coverage: 98.38% and project coverage change: +0.65 🎉

Comparison is base (271f812) 69.70% compared to head (6c5d8fd) 70.35%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #261      +/-   ##
==========================================
+ Coverage   69.70%   70.35%   +0.65%     
==========================================
  Files          28       28              
  Lines        2667     2685      +18     
==========================================
+ Hits         1859     1889      +30     
+ Misses        808      796      -12     

Impacted Files	Coverage Δ
src/Spaces/Jacobi/JacobiOperators.jl	85.20% <97.36%> (+4.87%)	⬆️
src/ApproxFunOrthogonalPolynomials.jl	90.00% <100.00%> (ø)
src/Spaces/Jacobi/Jacobi.jl	69.23% <100.00%> (+1.08%)	⬆️
src/Spaces/PolynomialSpace.jl	93.16% <100.00%> (-0.05%)	⬇️
...c/Spaces/Ultraspherical/UltrasphericalOperators.jl	80.18% <100.00%> (ø)

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