Add psycopg2 as an optional dependency and throw error at startup if db is not initialized

mautrix_telegram/__main__.py

@@ -14,6 +14,7 @@
 # You should have received a copy of the GNU Affero General Public License
 # along with this program.  If not, see <https://www.gnu.org/licenses/>.
 from itertools import chain
+import sys
 
 from alchemysession import AlchemySessionContainer
 
@@ -57,6 +58,10 @@ class TelegramBridge(Bridge):
 
     def prepare_db(self) -> None:
         super().prepare_db()
+        if not self.db.has_table("alembic_version"):
+            self.log.critical("alembic_version table not found. "
+                              "Did you forget to `alembic upgrade head`?")
+            sys.exit(10)
         init_db(self.db)
         self.session_container = AlchemySessionContainer(
             engine=self.db, table_base=Base, session=False,