feat: migration from attrs to pydantic (#49)

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Codecov Report

Attention: 8 lines in your changes are missing coverage. Please review.

Comparison is base (d1c86d4) 62.04% compared to head (ecbd2e2) 79.84%. Report is 2 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #65 +/- ## =========================================== + Coverage 62.04% 79.84% +17.79% =========================================== Files 19 19 Lines 1444 1424 -20 =========================================== + Hits 896 1137 +241 + Misses 548 287 -261 ``` | [Files](https://app.codecov.io/gh/bihealth/varfish-cli/pull/65?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=bihealth) | Coverage Δ | | |---|---|---| | [varfish\_cli/api/models.py](https://app.codecov.io/gh/bihealth/varfish-cli/pull/65?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=bihealth#diff-dmFyZmlzaF9jbGkvYXBpL21vZGVscy5weQ==) | `100.00% <100.00%> (ø)` | | | [varfish\_cli/api/project.py](https://app.codecov.io/gh/bihealth/varfish-cli/pull/65?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=bihealth#diff-dmFyZmlzaF9jbGkvYXBpL3Byb2plY3QucHk=) | `100.00% <100.00%> (ø)` | | | [varfish\_cli/api/varannos.py](https://app.codecov.io/gh/bihealth/varfish-cli/pull/65?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=bihealth#diff-dmFyZmlzaF9jbGkvYXBpL3ZhcmFubm9zLnB5) | `100.00% <100.00%> (ø)` | | | [varfish\_cli/cli/common.py](https://app.codecov.io/gh/bihealth/varfish-cli/pull/65?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=bihealth#diff-dmFyZmlzaF9jbGkvY2xpL2NvbW1vbi5weQ==) | `89.90% <100.00%> (ø)` | | | [varfish\_cli/cli/importer/\_\_init\_\_.py](https://app.codecov.io/gh/bihealth/varfish-cli/pull/65?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=bihealth#diff-dmFyZmlzaF9jbGkvY2xpL2ltcG9ydGVyL19faW5pdF9fLnB5) | `92.15% <100.00%> (+10.15%)` | :arrow_up: | | [varfish\_cli/cli/varannos.py](https://app.codecov.io/gh/bihealth/varfish-cli/pull/65?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=bihealth#diff-dmFyZmlzaF9jbGkvY2xpL3ZhcmFubm9zLnB5) | `100.00% <100.00%> (ø)` | | | [varfish\_cli/common.py](https://app.codecov.io/gh/bihealth/varfish-cli/pull/65?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=bihealth#diff-dmFyZmlzaF9jbGkvY29tbW9uLnB5) | `87.71% <ø> (+0.76%)` | :arrow_up: | | [varfish\_cli/parse\_ped.py](https://app.codecov.io/gh/bihealth/varfish-cli/pull/65?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=bihealth#diff-dmFyZmlzaF9jbGkvcGFyc2VfcGVkLnB5) | `100.00% <100.00%> (ø)` | | | [varfish\_cli/cli/importer/create.py](https://app.codecov.io/gh/bihealth/varfish-cli/pull/65?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=bihealth#diff-dmFyZmlzaF9jbGkvY2xpL2ltcG9ydGVyL2NyZWF0ZS5weQ==) | `77.24% <50.00%> (+51.87%)` | :arrow_up: | | [varfish\_cli/api/case.py](https://app.codecov.io/gh/bihealth/varfish-cli/pull/65?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=bihealth#diff-dmFyZmlzaF9jbGkvYXBpL2Nhc2UucHk=) | `50.69% <78.26%> (+22.48%)` | :arrow_up: |

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