Wrap values of 'INT64' type in BigQueryInt objects

[minodisk]

Fixes #54

Docs

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after:

[codecov[bot]]

Codecov Report

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

Project coverage is 60.88%. Comparing base (28d07d5) to head (0cb3397).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #56 +/- ## ======================================= Coverage 60.88% 60.88% ======================================= Files 20 20 Lines 698 698 Branches 126 126 ======================================= Hits 425 425 Misses 248 248 Partials 25 25 ```

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