add a valid postgresql-aiopg setuptools extra

Author: graingert

requirements.txt

@@ -1,7 +1,7 @@
 # Notes...
 # The JSONField tests require sqlalchemy 1.3+. Other cases work at lower versions.
 # The aiocontextvars package is only required as a backport for Python 3.6.
--e .[trio-postgresql,trio-mysql,mysql,sqlite,postgresql,postgresql+aiopg]
+-e .[trio-postgresql,trio-mysql,mysql,sqlite,postgresql,postgresql-aiopg]
 
 # Sync database drivers for standard tooling around setup/teardown/migrations.
 psycopg2-binary

setup.py

@@ -55,7 +55,8 @@ def get_packages(package):
         "postgresql": ["asyncpg"],
         "mysql": ["aiomysql"],
         "sqlite": ["aiosqlite"],
-        "postgresql+aiopg": ["aiopg"]
+        "postgresql+aiopg": ["aiopg"],
+        "postgresql-aiopg": ["aiopg"]
     },
     classifiers=[
         "Development Status :: 3 - Alpha",