[R-pkg-team] Bug#1102548: fixing #1102548: r-cran-dendextend autopkgtest fail

[Rebecca N. Palmer]

Control: tags -1 fixed-upstream

This is because this test implicitly requires DendSer, which isn't in 
Debian:
https://github.com/talgalili/dendextend/issues/154

Upstream 1.19.1 skips the test when this is not available.

Of the R team's currently open RC bugs, this is the only one where a new 
upstream version is likely to help.  (While the above implies that 
r-cran-dextend is not actually broken for users, it's still RC in the 
sense of not allowing r-cran-dextend in testing.)

Hence, I propose to update r-cran-dextend (and re-add r-cran-plotly's 
test-Depends that I removed because of this, #1104338) soon, not wait 
for the general post-release mass-update.