rvinecopulib 0.5.2.1.0

Release following the updates of vinecopulib to 0.5.2, see
https://github.com/vinecopulib/vinecopulib/releases. The most
relevant changes are summarized below.

NEW FEATURES

• single-integer constructors for dvine_structure()/cvine_structure(). (#203)

• add var_names = "hide" option in plot.vinecop_dist(). (#203)

• add function plot.rvine_matrix(). (#203)

BUG FIXES

• fix bug for (negative) tau to parameter conversion for Frank family. (#207)

• fix rare error rvine_structure_sim()/rvine_matrix_sim()

• safeguard "tll" family against comonotonic data.

• stabilize archimedean h-functions near independence.