get_googlemap: error using download.file() with 'https://'

Since commit dd6bf2da5a54b7bf14c30afe2ce2a6b98b114499, `get_googlemap()` is requesting the map via http instead of https, but since `download.file()` is called with `method = NULL` (`method = 'internal'` in most of the cases), 'https://' URLs are not supported in most of the cases, as stated in the documentation of `download.file()`, and the `get_googlemap()` or `get_map()` crashes with the following message:

```r
Error in download.file(url, destfile = destfile, quiet = !messaging,
mode = "wb") :
unsupported URL scheme
```

Please let me know if I'm wrong or if I can give more information.