Update code examples in R code and paper (arxiv) according to upcoming breaking changes in `paradox`

[PhilippBach]

DoubleMLReplicationCode/Code/doubleml_codechunks.R

Lines 246 to 251 in 9320dcc

	par_grids = list(
	"ml_l" = ParamSet$new(list(
	ParamDbl$new("lambda", lower = 0.05, upper = 0.1))),
	"ml_m" = ParamSet$new(list(
	ParamDbl$new("lambda", lower = 0.05, upper = 0.1))))

[PhilippBach]

Just updated the .tex file and substituted the paper on arxiv