fix: added check for missing release information for anomalous version

[art1f1c3R]

Summary

Fixing #1231, this PR introduces a check for when there exists an entry for a release, but no actual information inside that release.

Description of changes

A check for a non-empty release_metadata field (i.e. there exists information about the release) has been added to anomalous_version.py. The version extraction was moved under the publish days, years, and months parsing so that all HeuristicAnalyzerValueErrors are raised before results are considered. Additional unit tests were added to test_anomalous_version.py to reflect the bug and expected behaviour.

Related issues

Closes #1231.

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