A problem with InvalidOperationException and flake8 is fixed

Author: dmitry-lipetsk

testgres/__init__.py

@@ -61,7 +61,7 @@
     "NodeBackup", "testgres_config",
     "TestgresConfig", "configure_testgres", "scoped_config", "push_config", "pop_config",
     "NodeConnection", "DatabaseError", "InternalError", "ProgrammingError", "OperationalError",
-    "TestgresException", "ExecUtilException", "QueryException", "TimeoutException", "CatchUpException", "StartNodeException", "InitNodeException", "BackupException",
+    "TestgresException", "ExecUtilException", "QueryException", "TimeoutException", "CatchUpException", "StartNodeException", "InitNodeException", "BackupException", "InvalidOperationException",
     "XLogMethod", "IsolationLevel", "NodeStatus", "ProcessType", "DumpFormat",
     "PostgresNode", "NodeApp",
     "reserve_port", "release_port", "bound_ports", "get_bin_path", "get_pg_config", "get_pg_version",