[pybsddb] Migration tool?

[José María Mateos]

Hi,

I've been testing the old bsddb3 library (on Python 3.6) for a project 
I'm writing and it works quite well. Thanks a lot for supporting this 
library.

Recently, I've had to upgrade the Python version (to Python 3.11, for 
the time being), hence I installed the berkeleydb library.

However, the files I created with bsddb3 are not compatible. See:

```
db_cursor = berkeleydb.btopen('/path/to/file.db', 'c')
...
DBInvalidArgError: (22, 'Invalid argument -- BDB1009 /path/to/file.db: unsupported btree version: 10')

```

I have two questions about this:

1. Is there any tool to migrate old DBs to the newer version?

2. Is this kind of deprecation common, or I'm just encountering it 
because I made a large jump in versions? I see a lot of BerkeleyDB 
formats were dropped in the 18.1.0-pre announcement, so perhaps that's 
what I'm seeing here.

Thanks a lot!

-- 
José María (Chema) Mateos || https://rinzewind.org