CIDC-1421 allow jpg files for hande assay images

[JamesProvencher]

What

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Why

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How

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Remarks

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Checklist

Please include and complete the following checklist. You can mark an item as complete with the - [x] prefix:

• Tests - Added unit tests for new code, regression tests for bugs and updated the integration tests if required
• Formatting & Linting - black and flake8 have been used to ensure styling guidelines are met
• Type Annotations - All new code has been type annotated in the function signatures using type hints
• Docstrings - Docstrings have been provided for functions
• Documentation - Documentation in docs/ has be regenerated and README and CHANGELOG have been updated to explain major changes & new features
• Package version - Manually bumped the Schemas package version in cidc_schemas/__init__.py

[codeclimate]

Code Climate has analyzed commit 717278c and detected 0 issues on this pull request.

The test coverage on the diff in this pull request is 100.0% (50% is the threshold).

This pull request will bring the total coverage in the repository to 94.1% (0.0% change).

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