chg: dev: update setup file

- ignore mypy error when getting the version
- add minimum version of setuptools for dev

setup.py

@@ -10,7 +10,7 @@ if os.path.isfile('buku'):
     shutil.copyfile('buku', 'buku.py')
 
 with open('buku.py', encoding='utf-8') as f:
-    version = re.search('__version__ = \'([^\']+)\'', f.read()).group(1)
+    version = re.search('__version__ = \'([^\']+)\'', f.read()).group(1)  # type: ignore
 
 with open('README.md', encoding='utf-8') as f:
     long_description = f.read()
@@ -25,6 +25,7 @@ tests_require = [
     'pytest-cov',
     'pytest>=3.4.2',
     'PyYAML>=4.2b1',
+    'setuptools>=41.0.1',
     'vcrpy>=1.13.0',
 ]