Deepcell

🐛 Bug Fixes

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<summary>Validate parent lineage field as well as daughters. willgraf (76)</summary>

73 updated `is_valid_lineage` to do better of all cells. However, there is no extra validation of the `parent` field, which is used in the `isbi_utils` functions.

This PR adds some basic validation of the `parent` lineage field to improve the validation of the lineage objects.
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🐛 Bug Fixes

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<summary>`is_valid_lineage` should check if the daughter ID is valid. willgraf (70)</summary>

If a cell's daughter ID is not a valid track ID, then `is_valid_lineage` will crash due to a `KeyError`. Instead, it should catch this error and note the lineage as invalid.
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🚀 Features

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<summary>Support saving and loading trk/trks data to/from `BytesIO` msschwartz21 (68)</summary>

In the `data-registry`, we often read and write track data in memory in order to facilitate moving data to and from s3 buckets. This PR enables a `io.BytesIO()` object to be passed into `save_trks` and `load_trks` in place of a filepath. Additionally a new utility function `save_track_data` is introduced to serve as a base for `save_trks` and `save_trk` which are wrappers that allow saving to either `trk` or `trks`.
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🚀 Features

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<summary>Change `isbi_utils` from writing files to comparing in memory R-Ding (67)</summary>

What
* Replace writing to GT and result ISBI-style .txt files with saving an array of ISBI-style dictionaries and comparing those.
* Modifying `isbi_utils_tests` to test the new approach

Why
* Comparing in memory is quicker and allows for less chances of error
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🐛 Bug Fixes

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<summary>Cache the entire Python environment to speed up build times. willgraf (66)</summary>

What
* Cache the entire Python environment in the testing GitHub Action workflow.

Why
* [Drastically speed up build times](https://medium.com/ai2-blog/python-caching-in-github-actions-e9452698e98d).

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<details>
<summary>Support Python 3.9 willgraf (61)</summary>


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🐛 Bug Fixes

<details>
<summary>Compress `.trks` by using gzip compression when writing the tarfile. willgraf (64)</summary>

The third time's the charm! This is the same PR as 63, but removing the changes featured in 62.

This PR changes the writemode of `tarfile` to write in `w:gz`, or with gzip compression. The read mode of `tarfile` natively supports this.

Additionally, some related tests have been updated to use the `tmpdir` test fixture instead of creating their own temporary directory.
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Bugfixes

* Fixed bug where `resize()` would swap the x and y axes (32).