Issue 1219 warn of uncommitted DS

[PiispaH]

Re spine-tools/Spine-Toolbox#2459

Fixes spine-tools/Spine-Toolbox#1219

Checklist before merging

• [x] Documentation (also in Toolbox repo) is up-to-date
• [x] Release notes in Toolbox repo have been updated
• [x] Unit tests have been added/updated accordingly
• [x] Code has been formatted by black
• [x] Unit tests pass
• [x] Change requirements back to 0.8-dev branch

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 89.65517% with 3 lines in your changes are missing coverage. Please review.

Project coverage is 61.70%. Comparing base (a1b6b12) to head (0e3d2f3).

:exclamation: Current head 0e3d2f3 differs from pull request most recent head daa2f82. Consider uploading reports for the commit daa2f82 to get more accurate results

Files	Patch %	Lines
spine_items/data_store/data_store.py	89.65%	0 Missing and 3 partials :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## 0.8-dev #177 +/- ## =========================================== + Coverage 61.68% 61.70% +0.02% =========================================== Files 190 190 Lines 17655 17683 +28 Branches 2890 2896 +6 =========================================== + Hits 10890 10912 +22 - Misses 6183 6187 +4 - Partials 582 584 +2 ```

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