setuptoolsBuildHook: lint with ShellCheck

Changed files
+2
pkgs
development
interpreters
+2
pkgs/development/interpreters/python/hooks/setuptools-build-hook.sh
···
# Setup hook for setuptools.
echo "Sourcing setuptools-build-hook"
setuptoolsBuildPhase() {
···
# Setup hook for setuptools.
+
# shellcheck shell=bash
+
echo "Sourcing setuptools-build-hook"
setuptoolsBuildPhase() {