How to install pytorch torchvision via Conda.jl?

According to pytorch, the command to install torch vision via conda is:
`conda install pytorch torchvision -c pytorch`

What is the equivalent Conda.add command for that? While it is happy with `Conda.add("pytorch")`, it is not happy with `Conda.add("torchvision")`. I tried different combination of words in `pytorch torchvision -c pytorch` in Conda.add without success.

Here is the error message:
```
julia> Conda.add("torchvision")
[ Info: Running `conda install -y torchvision` in root environment
Collecting package metadata (current_repodata.json): done
Solving environment: failed with initial frozen solve. Retrying with flexible solve.
Collecting package metadata (repodata.json): done
Solving environment: failed with initial frozen solve. Retrying with flexible solve.

PackagesNotFoundError: The following packages are not available from current channels:

- torchvision

Current channels:

- https://repo.anaconda.com/pkgs/main/osx-64
- https://repo.anaconda.com/pkgs/main/noarch
- https://repo.anaconda.com/pkgs/r/osx-64
- https://repo.anaconda.com/pkgs/r/noarch

To search for alternate channels that may provide the conda package you're
looking for, navigate to

https://anaconda.org

and use the search bar at the top of the page.

ERROR: failed process: Process(setenv(`/Users/donglai/.julia/conda/3/bin/conda install -y torchvision`,["XPC_FLAGS=0x0", "PATH=/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin", "PWD=/Users/donglai", "XPC_SERVICE_NAME=0", "TERM_PROGRAM=Apple_Terminal", "SHELL=/bin/zsh", "__CF_USER_TEXT_ENCODING=0x1F5:0x0:0x0", "TMPDIR=/var/folders/r0/prgb84yj2tgb68tgr497bnx80000gn/T/", "CONDARC=/Users/donglai/.julia/conda/3/condarc-julia.yml", "LANG=en_US.UTF-8" … "SSH_AUTH_SOCK=/private/tmp/com.apple.launchd.mOaXDpVV7P/Listeners", "OLDPWD=/Users/donglai/GitHub", "_=/Applications/Julia-1.4.app/Contents/Resources/julia/bin/julia", "USER=donglai", "SECURITYSESSIONID=186a6", "TERM=xterm-256color", "HOME=/Users/donglai", "TERM_PROGRAM_VERSION=433", "OPENBLAS_MAIN_FREE=1", "PYTHONIOENCODING=UTF-8"]), ProcessExited(1)) [1]

Stacktrace:
[1] pipeline_error at ./process.jl:525 [inlined]
[2] run(::Cmd; wait::Bool) at ./process.jl:440
[3] run at ./process.jl:438 [inlined]
[4] runconda(::Cmd, ::String) at /Users/donglai/.julia/packages/Conda/3rPhK/src/Conda.jl:114
[5] add(::String, ::String; channel::String) at /Users/donglai/.julia/packages/Conda/3rPhK/src/Conda.jl:188
[6] add at /Users/donglai/.julia/packages/Conda/3rPhK/src/Conda.jl:187 [inlined] (repeats 2 times)
[7] top-level scope at REPL[116]:1
```