PR to support LODES8 / 2020 LODES

[walkerke]

Hi @jamgreen @dillonma -

This PR addresses #30 and adds support for LODES8 (2020 Census blocks) as well as LODES5 (2000 Census blocks). The main update is a new argument in grab_lodes(), version, which supports specification of the version.

I've updated the test suite including a test for the use of LODES7, and all tests pass. Would you mind taking a look when you get the chance and see if this implementation fits with your approach?

[walkerke]

library(tigris)
library(lehdr)
library(tidyverse)

pdx_metro <- tracts("OR", c("Multnomah", "Washington", "Clackamas"), year = 2020, cb = TRUE)

or_wac <- grab_lodes("or", year = 2020, lodes_type = "wac",
                     agg_geo = "tract")

pdx_naics62 <- pdx_metro %>%
  select(GEOID) %>%
  inner_join(or_wac, by = c("GEOID" = "w_tract")) %>%
  transmute(
    GEOID = GEOID,
    prop_naics62 = CNS16 / C000
  )

ggplot(pdx_naics62, aes(fill = prop_naics62)) + 
  theme_void() + 
  geom_sf() + 
  scale_fill_viridis_c(labels = scales::label_percent())