This fixes the situtation where, if `/usr/share/zoneinfo` was
inaccessible/didn't otherwise exist, `howard-hinnant-date` would
download and drop a `~/Downloads/tzdata` directory containing some
timezone information from IANA [1]. To avoid this, we make use of the
`tzdata`'s `zoneinfo`, preventing the dropping of random directories and
files.
[1] https://data.iana.org/time-zones/releases/tzdata2019c.tar.gz
