Revert "SA14: Pin some dependency packages to retain compatibility with Python 3.6"

After support for Python 3.6 has been dropped, this is no longer needed.

This reverts commit 25da05e.

Author: amotl

setup.py

@@ -67,10 +67,7 @@ def read(path):
         test=['zope.testing>=4,<5',
               'zc.customdoctests>=1.0.1,<2',
               'stopit>=1.1.2,<2'],
-        sqlalchemy=['sqlalchemy>=1.0,<1.5',
-                    'geojson>=2.5.0',
-                    'importlib-metadata<4',
-                    'typing-extensions<4']
+        sqlalchemy=['sqlalchemy>=1.0,<1.5', 'geojson>=2.5.0']
     ),
     python_requires='>=3.4',
     install_requires=requirements,