Python bindings: Fix editable install + Execute Python2.7 workflow tests (#2044)

* Python binding:
- Added missing `license` field in pyproject.toml file
- Fixed editable mode install and some more code cleanup in setup.py
- Refreshed README.md
- Replaced f-string formatter in tests with `format` method in order to be py2-compatible
- Fixed typos
- PEP8 fixes

* GitHub Action: Install Python2.7 and run tests for re-tagged wheels on native arch runners only

* Python bindings:
- Use #x formatter to format hex values

bindings/python/pyproject.toml

@@ -12,6 +12,7 @@ authors = [
 description = "Unicorn CPU emulator engine"
 readme = "README.md"
 keywords = ["emulation", "qemu", "unicorn"]
+license = { text = "BSD License" }
 classifiers = [
     'License :: OSI Approved :: BSD License',
     'Programming Language :: Python :: 2.7',