Geobr

Minor changes
* Fixed unnecessary warning about internet connection. Closes 200.

**Minor changes**

- The `read_municipality()` has a new parameter `keep_areas_operacionais`, which allows users to control wether the data should keep the polygons of Lagoas dos Patos and Lagoa Mirim in the State of Rio Grande do Sul (considered as areas estaduais operacionais). The default `FALSE` drops these two polygons. Closes 176.
- Functions now include a `cache` parameter that allows users to decide whehter to keep files in cache or to force downloading them again. At the moment, files are only cached during the R session, but this is a step towards a future version of {geobr} when files will be based on permanent caching.
- Now using `curl::multi_download()` to download files in parallel
- Removed dependency on the {httr} package
- {geobr} now imports {fs} to use robust cross-platform file system operations
- Simplified and streamlined internal functions

**Major changes**

- Function `read_health_facilities()` now has a new parameter `date`, which will allow users to access data for different dates of reference. The plan is to have at least one update of this data set per year. Closes 334.
- Functions `read_urban_area()` and `read_metro_area()` now have a new parameter `code_state`, which will allow users to filter selected states. Closes 338

**Bug fix**
- Using `data.table::rbindlist()` to rind data was throwing errors when some observations were of class `POLYGONS` and others were `MULTIPOLYGONS`. This has now been replaced with `dplyr::bind_rows()` at a very small performance penalty. Closes 346.

**New data**
- schools for 2023
- health facilities for 202303
- census tracts for 2020 and 2022

**CRAN request**
- Fixed issue to make sure geobr uses suggested packages conditionally

**Minor changes**
- Fixed non-ASCII characters in data `geobr::grid_state_correspondence_table()`

**CRAN request**
- geobr now uses suggested packages conditionally

**New function**
- `read_capitals()` to download either a spatial `sf` object with the location of the municipal seats (sede dos municipios) of state capitals, or a `data.frame` with the names of codes of state capitals. [Closes 243](https://github.com/ipeaGIT/geobr/issues/243)

**Minor changes**
- Update intro vignette to show how to use geobr together with the new [**censobr**](https://ipeagit.github.io/censobr/index.html) sister package.

**Bug fixes**

- fixed bug from conflict between `sf` and `data.table` that was messing with plot extent. [Closes 284](https://github.com/ipeaGIT/geobr/issues/284).
- fixed bug from conflicts between `plotly` and `data.table`. [Closes 279](https://github.com/ipeaGIT/geobr/issues/279).
- fixed bug in `cep_to_state()` function. [Closes 317](https://github.com/ipeaGIT/geobr/issues/317).
- fixed bug in progress bar. [Closes 154](https://github.com/ipeaGIT/geobr/issues/154).
- The `lookup_muni()` and `download_metadata()` functions are now more robust to internet connection failures.