The R Project core team has provided a helpful guide entitled "Who Did What? The Roles of R Package Authors and How to Refer to Them".
Like many journals these days, R package
CITATION files allow you to delineate the contributions of each individual author with three letter MARC codes. A quote from the paper linked above:
"ths" (Thesis advisor): Thesis advisor, if the package is part of a thesis.
Clearly the core team intended to make it possible to list a supervisor as an author. Note that there is also a
fnd code for funders. As you may know, R includes a
citation() function to help citing a package. Only some author roles appear when calling this function. Please refer to documentation for further information.
I work in medicine, and so I try to follow the NIH guidelines when determining authorship. As you can see, providing financial support alone does not confer authorship. Therefore, I would probably not include your advisor if they only provided funding.
During my PhD, I published an R package with a collaborator. I did not include my thesis advisor as an author.