Fix seq generators for enum tables in postgres

This attempts to insert a temporary entry into each enum table until it
succeeds. It re-synchronizes the postgres sequence generators with the max id
of the table.

Fixes #883 and #880

data/migrations/versions/41f4587c84ae_add_jwt_authentication_login_service.py

@@ -17,7 +17,7 @@ import sqlalchemy as sa
 def upgrade(tables):
     op.bulk_insert(tables.loginservice,
     [
-        {'id': 5, 'name':'jwtauthn'},
+        {'name':'jwtauthn'},
     ])