use tox extras

per tox devs [1] it's better we use "extras" explcitly
rather than putting our extras in deps

[1] https://github.com/tox-dev/tox/issues/2898#issuecomment-1407921041

Change-Id: Ib57bc1277a462b270e243b1bb4cdb55a80449256

tox.ini

@@ -5,36 +5,37 @@ envlist = py
 [testenv]
 cov_args=--cov=sqlalchemy --cov-report term --cov-append --cov-report xml --exclude-tag memory-intensive --exclude-tag timing-intensive -k "not aaa_profiling"
 
-# new opt as of tox 4.4.0 was set to True causing it to dump the
-# deps below into a constraints file, while requirements of the
-# form ".[aiosqlite]" are not valid constraints, those are requirements
-constrain_package_deps=false
+# this needs to be set as of tox 4.4.0 *if* we have extras (e.g. .[aiosqlite])
+# inside of deps.  But we put them in extras now.
+# see https://github.com/tox-dev/tox/issues/2898
+# constrain_package_deps=false
 
 usedevelop=
      cov: True
 
+extras=
+     sqlite: aiosqlite
+     sqlite_file: aiosqlite
+     sqlite_file: sqlcipher; python_version < '3.10'
+     postgresql: postgresql
+     postgresql: postgresql_asyncpg
+     postgresql: postgresql_pg8000
+     postgresql: postgresql_psycopg
+
+     mysql: mysql
+     mysql: pymysql
+     mysql: asyncmy
+
+#     mysql: mariadb_connector
+
+     oracle: oracle
+     oracle: oracle_oracledb
+     mssql: mssql
+
 deps=
      pytest>=7.0.0rc1,<8
      pytest-xdist
 
-     sqlite: .[aiosqlite]
-     sqlite_file: .[aiosqlite]
-     sqlite_file: .[sqlcipher]; python_version < '3.10'
-     postgresql: .[postgresql]
-     postgresql: .[postgresql_asyncpg]
-     postgresql: .[postgresql_pg8000]
-     postgresql: .[postgresql_psycopg]
-
-     mysql: .[mysql]
-     mysql: .[pymysql]
-     mysql: .[asyncmy]
-
-#     mysql: .[mariadb_connector]
-
-     oracle: .[oracle]
-     oracle: .[oracle_oracledb]
-     mssql: .[mssql]
-
      dbapimain-sqlite: git+https://github.com/omnilib/aiosqlite.git#egg=aiosqlite
      dbapimain-sqlite: git+https://github.com/coleifer/sqlcipher3.git#egg=sqlcipher3