python-setup: Allow newest virtualenv

Context for previous version is
#862

Locally, I was able to install `20.15.1` with Python2.

I don't see any reason why python3 version should be restricted.

python-setup/install_tools.ps1

@@ -5,8 +5,8 @@ py -3 -m pip install --user --upgrade pip setuptools wheel
 
 # virtualenv is a bit nicer for setting up virtual environment, since it will provide up-to-date versions of
 # pip/setuptools/wheel which basic `python3 -m venv venv` won't
-py -2 -m pip install --user 'virtualenv<20.11'
-py -3 -m pip install --user 'virtualenv<20.11'
+py -2 -m pip install --user 'virtualenv!=20.12.0'
+py -3 -m pip install --user virtualenv
 
 # We aren't compatible with poetry 1.2
 py -3 -m pip install --user "poetry>=1.1,<1.2"

python-setup/install_tools.sh

@@ -15,7 +15,7 @@ python3 -m pip install --user --upgrade pip setuptools wheel
 
 # virtualenv is a bit nicer for setting up virtual environment, since it will provide up-to-date versions of
 # pip/setuptools/wheel which basic `python3 -m venv venv` won't
-python3 -m pip install --user 'virtualenv<20.11'
+python3 -m pip install --user virtualenv
 
 # We install poetry with pip instead of the recommended way, since the recommended way
 # caused some problem since `poetry run` gives output like:
@@ -42,5 +42,5 @@ if command -v python2 >/dev/null 2>&1; then
 
 	python2 -m pip install --user --upgrade pip setuptools wheel
 
-	python2 -m pip install --user 'virtualenv<20.11'
+	python2 -m pip install --user 'virtualenv!=20.12.0'
 fi