Bug#1102590: r-cran-fansi fails to migrate to testing

[Rebecca N. Palmer]

It's r-base 4.5 that's blocking r-cran-fansi, not the other way round. 
It looks like the reason is that r-cran-fansi's tests (possibly 
unintentionally) assert that it doesn't produce warnings, while loading 
a package built in R 4.5 into R 4.4 triggers a warning.