And log the metadata dictionary.
This allows easier debugging:
```
swh-lister_1 | [2022-01-24 13:31:06,174: INFO/ForkPoolWorker-1] Found 2 poms.
swh-lister_1 | [2022-01-24 13:31:06,174: INFO/ForkPoolWorker-1] Fetching poms..
swh-lister_1 | [2022-01-24 13:31:06,174: INFO/ForkPoolWorker-1] Fetching URL https://repo1.maven.org/maven2/al/aldi/sprova4j/0.1.0/sprova4j-0.1.0.pom with params {}
swh-lister_1 | [2022-01-24 13:31:06,210: INFO/ForkPoolWorker-1] * Yielding pom https://repo1.maven.org/maven2/al/aldi/sprova4j/0.1.0/sprova4j-0.1.0.pom: {'type': 'scm', 'doc': 1, 'url': 'scm:https://github.com/aldialimucaj/sprova4j.git', 'project': 'al.aldi.sprova4j'}
swh-lister_1 | [2022-01-24 13:31:06,215: INFO/ForkPoolWorker-1] Fetching URL https://repo1.maven.org/maven2/al/aldi/sprova4j/0.1.1/sprova4j-0.1.1.pom with params {}
swh-lister_1 | [2022-01-24 13:31:06,222: INFO/ForkPoolWorker-1] * Yielding pom https://repo1.maven.org/maven2/al/aldi/sprova4j/0.1.1/sprova4j-0.1.1.pom: {'type': 'scm', 'doc': 3, 'url': 'scm:https://github.com/aldialimucaj/sprova4j.git', 'project': 'al.aldi.sprova4j'},
```