Explicitly depend on setuptools

Instead of assuming it's already present.

setup.py

@@ -161,6 +161,7 @@ setup(
     author="Frida Developers",
     author_email="[email protected]",
     url="https://frida.re",
+    install_requires=["setuptools"],
     license="wxWindows Library Licence, Version 3.1",
     keywords="frida debugger dynamic instrumentation inject javascript windows macos linux ios iphone ipad android qnx",
     classifiers=[