reduce dependencies

[maxheld83]

the DESCRIPTION is horribly bloated.

We can probably do without much in there.

At least those here just had to be added to appease rsconnect::deployApp():

    DBI (>= 1.1.0),
    dbplyr (>= 1.4.3),
    haven (>= 2.2.0),
    lubridate (>= 1.7.8),
    modelr (>= 0.1.7),
    reprex (>= 0.3.0),
    rvest (>= 0.3.5),
    selectr (>= 0.4.2)