Add flake8 linter script

test/lint/lint-python.sh

@@ -0,0 +1,16 @@
+#!/usr/bin/env bash
+# Based on Bitcoin Core's test/lint/lint-python.sh
+
+if ! command -v flake8 > /dev/null; then
+    echo "Skipping Python linting since flake8 is not installed."
+    exit 0
+elif flake8 --version | grep -q "Python 2"; then
+    echo "Skipping Python linting since flake8 is running under Python 2. Install the Python 3 version of flake8."
+    exit 0
+fi
+
+if [[ $# == 0 ]]; then
+    flake8 $(git ls-files "*.py")
+else
+    flake8 "$@"
+fi