Fix show method for TableModels

[andreasnoack]

Similar to and surfaced by JuliaStats/StatsBase.jl#986

After JuliaStats/StatsBase.jl#986, the show method here gives

julia> m
StatsModels.TableRegressionModel{DummyMod, Matrix{Float64}}

y ~ 1 + x1 + x2 + x1 & x2

Coefficients:
CoefTable(Any[[1.0, 2.0, 3.0, 4.0]], ["'beta' value"], ["(Intercept)", "x1", "x2", "x1 & x2"], 0, 0)

and with the fix here it becomes

julia> m
StatsModels.TableRegressionModel{DummyMod, Matrix{Float64}}

y ~ 1 + x1 + x2 + x1 & x2

Coefficients:
─────────────────────────
             'beta' value
─────────────────────────
(Intercept)           1.0
x1                    2.0
x2                    3.0
x1 & x2               4.0
─────────────────────────

[nalimilan]

IIUC we should release this soon and before JuliaStats/StatsBase.jl#986 so that when StatsBase is released nothing breaks, right? It could also make sense to check on JuliaHub whether there are other packages relying on this old behavior. I hadn't realized it would be so breaking.

[andreasnoack]

IIUC we should release this soon and before JuliaStats/StatsBase.jl#986

It was already released with v0.34.10 so I'll release this right away. I'll also make a code search on juliahub.com to see if I can find other similar use cases that would need to be adjusted.