Test download issues

[visr]

Some of the Natural Earth file downloads in the tests seem to be failing both in CI and locally.
Perhaps we should replace the RemoteFiles solution with something like yeesian/ArchGDAL.jl#154.

[ Info: Downloading file '110m_physical\ne_110m_land.shx' from 'https://github.com/nvkelso/natural-earth-vector/raw/v4.1.0/110m_physical\ne_110m_land.shx' with cURL.
[ Info: Downloading file '110m_physical\ne_110m_land.shp' from 'https://github.com/nvkelso/natural-earth-vector/raw/v4.1.0/110m_physical\ne_110m_land.shp' with cURL.
[ Info: Downloading file '110m_cultural\ne_110m_populated_places_simple.shp' from 'https://github.com/nvkelso/natural-earth-vector/raw/v4.1.0/110m_cultural\ne_110m_populated_places
_simple.shp' with cURL.
[ Info: Downloading file '110m_cultural\ne_110m_populated_places_simple.dbf' from 'https://github.com/nvkelso/natural-earth-vector/raw/v4.1.0/110m_cultural\ne_110m_populated_places
_simple.dbf' with cURL.
[ Info: Downloading file '110m_physical\ne_110m_land.dbf' from 'https://github.com/nvkelso/natural-earth-vector/raw/v4.1.0/110m_physical\ne_110m_land.dbf' with cURL.
[ Info: Downloading file '110m_physical\ne_110m_coastline.shp' from 'https://github.com/nvkelso/natural-earth-vector/raw/v4.1.0/110m_physical\ne_110m_coastline.shp' with cURL.
[ Info: Downloading file '110m_physical\ne_110m_coastline.shx' from 'https://github.com/nvkelso/natural-earth-vector/raw/v4.1.0/110m_physical\ne_110m_coastline.shx' with cURL.
[ Info: Downloading file '110m_physical\ne_110m_coastline.dbf' from 'https://github.com/nvkelso/natural-earth-vector/raw/v4.1.0/110m_physical\ne_110m_coastline.dbf' with cURL.
[ Info: Downloading file '110m_cultural\ne_110m_populated_places_simple.shx' from 'https://github.com/nvkelso/natural-earth-vector/raw/v4.1.0/110m_cultural\ne_110m_populated_places
_simple.shx' with cURL.
Shapefile: Error During Test at C:\Users\visser_mn\.julia\dev\Shapefile\test\runtests.jl:83
  Got exception outside of a @test
  LoadError: TaskFailedException:
  IOError: open: no such file or directory (ENOENT)
  Stacktrace:
   [1] uv_error at .\libuv.jl:97 [inlined]
   [2] open(::String, ::UInt16, ::UInt64) at .\filesystem.jl:87
   [3] sendfile(::String, ::String) at .\file.jl:940
   [4] cp(::String, ::String; force::Bool, follow_symlinks::Bool) at .\file.jl:351
   [5] rename(::String, ::String; force::Bool) at .\file.jl:927
   [6] rename at .\file.jl:924 [inlined]
   [7] #mv#13 at .\file.jl:393 [inlined]
   [8] download(::RemoteFiles.CURL, ::RemoteFile; verbose::Bool, quiet::Bool, force::Bool, retries::Int64) at C:\Users\visser_mn\.julia\packages\RemoteFiles\QXzCt\src\download.jl:8
6
   [9] download(::RemoteFile; kwargs::Base.Iterators.Pairs{Symbol,Bool,Tuple{Symbol,Symbol,Symbol},NamedTuple{(:quiet, :verbose, :force),Tuple{Bool,Bool,Bool}}}) at C:\Users\visser
_mn\.julia\packages\RemoteFiles\QXzCt\src\download.jl:22
   [10] (::RemoteFiles.var"#43#44"{Bool,Bool,RemoteFile})() at .\task.jl:356

  ...and 8 more exception(s).

  Stacktrace:
   [1] sync_end(::Channel{Any}) at .\task.jl:314
   [2] macro expansion at .\task.jl:333 [inlined]
   [3] download(::RemoteFileSet; quiet::Bool, verbose::Bool, force::Bool) at C:\Users\visser_mn\.julia\packages\RemoteFiles\QXzCt\src\RemoteFiles.jl:268
   [4] download(::RemoteFileSet) at C:\Users\visser_mn\.julia\packages\RemoteFiles\QXzCt\src\RemoteFiles.jl:267
   [5] top-level scope at C:\Users\visser_mn\.julia\dev\Shapefile\test\table.jl:36
   [6] include(::String) at .\client.jl:457
   [7] top-level scope at C:\Users\visser_mn\.julia\dev\Shapefile\test\runtests.jl:142
   [8] top-level scope at C:\buildbot\worker\package_win64\build\usr\share\julia\stdlib\v1.5\Test\src\Test.jl:1115
   [9] top-level scope at C:\Users\visser_mn\.julia\dev\Shapefile\test\runtests.jl:85
   [10] include(::String) at .\client.jl:457
   [11] top-level scope at none:6
   [12] eval(::Module, ::Any) at .\boot.jl:331
   [13] exec_options(::Base.JLOptions) at .\client.jl:272
   [14] _start() at .\client.jl:506
  in expression starting at C:\Users\visser_mn\.julia\dev\Shapefile\test\table.jl:36