remove sqlalchemy upper limit version (#1142)

Author: lwatskot

contrib/opencensus-ext-sqlalchemy/setup.py

@@ -42,7 +42,7 @@
     long_description=open('README.rst').read(),
     install_requires=[
         'opencensus >= 0.9.dev0, < 1.0.0',
-        'SQLAlchemy >= 1.1.14, < 1.3.24',  # https://github.com/sqlalchemy/sqlalchemy/issues/6168 # noqa: E501
+        'SQLAlchemy >= 1.1.14',
     ],
     extras_require={},
     license='Apache-2.0',