CompatHelper: bump compat for BioStructures to 2, (keep existing compat)

[github-actions[bot]]

This pull request changes the compat entry for the BioStructures package from 1 to 1, 2. This keeps the compat entries for earlier versions.

Note: I have not tested your package with this new compat entry. It is your responsibility to make sure that your package tests pass before you merge this pull request.

[codecov[bot]]

Codecov Report

Base: 83.63% // Head: 83.63% // No change to project coverage :thumbsup:

Coverage data is based on head (58b7245) compared to base (d547a24). Patch has no changes to coverable lines.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #116 +/- ## ======================================= Coverage 83.63% 83.63% ======================================= Files 33 33 Lines 3936 3936 ======================================= Hits 3292 3292 Misses 644 644 ``` Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=JuliaMolSim). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=JuliaMolSim)

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