Python setup: Fix URL for Python 2.7 pip install

This URL changed upstream. Fix it by using the same upstream URL as the LGTM Python image.
We can revisit separately whether to drop the Python 2 pip installation entirely.

python-setup/install_tools.sh

@@ -31,7 +31,7 @@ python3 -m pip install --user pipenv
 if command -v python2 &> /dev/null; then
 	# Setup Python 2 dependency installation tools.
 	# The Ubuntu 20.04 GHA environment does not come with a Python 2 pip
-	curl --location --fail https://bootstrap.pypa.io/get-pip.py | python2
+	curl --location --fail https://bootstrap.pypa.io/2.7/get-pip.py | python2
 
 	python2 -m pip install --user --upgrade pip setuptools wheel