S3 region can be customized in credsFromSecret

[pyjavo]

Right now, the region 'eu-west-1' is hardcoded in the following line

pgdump-aws-lambda/lib/config.js

Line 5 in 690f0a3

S3_REGION: 'eu-west-1',

I think it would be helpful to be able to change the region per project.