Test command doesn't seem to work on win64

- [X] I read [the conda-forge documentation](https://conda-forge.org/docs/user/introduction.html#how-can-i-install-packages-from-conda-forge) and could not find the solution for my problem there.

Issue:

Hi,
After installing parallel, my first try was to call it directly by its name but the command was not found. AfterI verifiying that .\env\Library\bin\parallel existed, I came here and found out in [meta.yaml](https://github.com/conda-forge/parallel-feedstock/blob/master/recipe/meta.yaml) that it needs to be called with bash.

I have tried the command listed in your test but without sucess :

> bash -c 'export SHELL=`cygpath -u "$BASH"`; parallel --plain --version || true'

What it is the correct way to call this command ?

Regards,
JR

Environment (conda list):

```
$ conda list
# packages in environment at D:\conda_env\json_env:
#
# Name Version Build Channel
ca-certificates 2020.12.5 h5b45459_0 conda-forge
certifi 2020.12.5 py39hcbf5309_0 conda-forge
m2-base 1.0.0 3 msys2
m2-bash 4.3.042 5 msys2
m2-bash-completion 2.3 2 msys2
m2-catgets 1.1 3 msys2
m2-coreutils 8.25 102 msys2
m2-dash 0.5.8 2 msys2
m2-file 5.25 2 msys2
m2-filesystem 2016.04 4 msys2
m2-findutils 4.6.0 2 msys2
m2-gawk 4.1.3 2 msys2
m2-gcc-libs 5.3.0 4 msys2
m2-gettext 0.19.7 4 msys2
m2-gmp 6.1.0 3 msys2
m2-grep 2.22 4 msys2
m2-gzip 1.7 2 msys2
m2-inetutils 1.9.2 2 msys2
m2-info 6.0 2 msys2
m2-less 481 2 msys2
m2-libasprintf 0.19.7 4 msys2
m2-libcatgets 1.1 3 msys2
m2-libcrypt 1.3 2 msys2
m2-libgettextpo 0.19.7 4 msys2
m2-libiconv 1.14 3 msys2
m2-libintl 0.19.7 4 msys2
m2-liblzma 5.2.2 2 msys2
m2-libpcre 8.38 2 msys2
m2-libreadline 6.3.008 8 msys2
m2-libutil-linux 2.26.2 2 msys2
m2-libxml2 2.9.2 3 msys2
m2-mintty 1!2.2.3 2 msys2
m2-mpfr 3.1.4 2 msys2
m2-msys2-launcher-git 0.3.28.860c495 2 msys2
m2-msys2-runtime 2.5.0.17080.65c939c 3 msys2
m2-ncurses 6.0.20160220 2 msys2
m2-sed 4.2.2 3 msys2
m2-tftp-hpa 5.2 2 msys2
m2-time 1.7 2 msys2
m2-ttyrec 1.0.8 2 msys2
m2-tzcode 2015.e 2 msys2
m2-util-linux 2.26.2 2 msys2
m2-which 2.21 3 msys2
m2-zlib 1.2.8 4 msys2
massedit 0.69.1 pypi_0 pypi
msys2-conda-epoch 20160418 1 msys2
nodejs 15.3.0 h57928b3_0 conda-forge
openssl 1.1.1i h8ffe710_0 conda-forge
parallel 20200322 0 conda-forge
perl 5.32.0.1 h57928b3_0 conda-forge
pip 20.3.3 py39haa95532_0
python 3.9.1 h6244533_2
python_abi 3.9 1_cp39 conda-forge
setuptools 51.0.0 py39haa95532_2
sqlite 3.33.0 h2a8f88b_0
tzdata 2020d h14c3975_0
vc 14.2 h21ff451_1
vs2015_runtime 14.28.29325 h5e1d092_0 conda-forge
wheel 0.36.2 pyhd3eb1b0_0
wincertstore 0.2 py39h2bbff1b_0
zlib 1.2.11 h62dcd97_4
```

Details about conda and system ( conda info ):

```
$ conda info

active environment : json_env
active env location : D:\conda_env\json_env
shell level : 2
user config file : C:\Users\admjrmorreale\.condarc
populated config files : C:\Users\admjrmorreale\.condarc
conda version : 4.9.2
conda-build version : not installed
python version : 3.8.5.final.0
virtual packages : __cuda=11.0=0
__win=0=0
__archspec=1=x86_64
base environment : C:\ProgramData\Miniconda3 (writable)
channel URLs : https://repo.anaconda.com/pkgs/main/win-64
https://repo.anaconda.com/pkgs/main/noarch
https://repo.anaconda.com/pkgs/r/win-64
https://repo.anaconda.com/pkgs/r/noarch
https://repo.anaconda.com/pkgs/msys2/win-64
https://repo.anaconda.com/pkgs/msys2/noarch
package cache : C:\ProgramData\Miniconda3\pkgs
C:\Users\admjrmorreale\.conda\pkgs
C:\Users\admjrmorreale\AppData\Local\conda\conda\pkgs
envs directories : D:\conda_env
C:\ProgramData\Miniconda3\envs
C:\Users\admjrmorreale\.conda\envs
C:\Users\admjrmorreale\AppData\Local\conda\conda\envs
platform : win-64
user-agent : conda/4.9.2 requests/2.25.1 CPython/3.8.5 Windows/10 Windows/10.0.17763
administrator : True
netrc file : None
offline mode : False
```

Start with recipe/meta.yaml and the Windows test command shown in the issue, then reproduce it in the reported win-64 conda environment. Determine whether the command or test setup is incorrect; done means the documented/tested invocation works on win-64 or the limitation is clearly recorded.

Written by the indexing model from the issue text.