update install requires to drop quotes

Author: Ziyang Liu

setup.py

@@ -74,7 +74,7 @@ def get_version():
     license='BSD License',
     packages=['markdown', 'markdown.extensions'],
     python_requires='>=3.6',
-    install_requires=["importlib-metadata>='4.4';python_version<'3.10'"],
+    install_requires=["importlib-metadata>=4.4;python_version<'3.10'"],
     extras_require={
         'testing': [
             'coverage',