Add type hints to importinfo.py and add repr to ImportInfo

[lieryan]

Description

• Add repr to ImportInfo
• Add type hints to importinfo.py

Checklist (delete if not relevant):

• [x] I have added tests that prove my fix is effective or that my feature works
• [x] I have updated CHANGELOG.md

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 94.97%. Comparing base (14d6fd2) to head (3f89161).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #787 +/- ## ========================================== + Coverage 94.88% 94.97% +0.08% ========================================== Files 135 135 Lines 26403 26405 +2 ========================================== + Hits 25053 25077 +24 + Misses 1350 1328 -22 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.