Support .pgpass files for migra

[waterkip]

This eases the whole connection URI setup for developers who make use of the
.pgpass file.

Signed-off-by: Wesley Schwengle wesley@opndev.io

[waterkip]

Hi, I didn't wrote a test for it because I'm too dumb I guess to get a working developer environment. So I did tests with my own setup which work.

Test prerequisites:

• A .pgpass file:

localhost:5432:*:yourdbuser:yourdbpassword

• Have two databases, eg foo and bar

How to test:

• invoke migra as usual, but without your username and password, in this case I assume your local user equals the postgres username:

   migra \
     postgresql://localhost/foo \
     postgresql://localhost/bar \
     --unsafe --ignore-extension-versions

• This should yield a connection

• invoke migra as usual, but a with username but without a password:

   migra \
     postgresql://yourdbuser@localhost/foo \
     postgresql://yourdbuser@localhost/bar \
     --unsafe --ignore-extension-versions

• This should yield a connection

• invoke migra as usual, but a with username but without a password and make sure you have a DB named the same as your user::

   migra \
     postgresql://yourdbuser@localhost/ \
     postgresql://yourdbuser@localhost/bar \
     --unsafe --ignore-extension-versions

• This should yield a connection

When you remove the .pgpass file you should not get a connection and migra fails as it did in the past.