Alchemista

Feature
* Added transform argument to fields_from and model_from ([`b87a907`](https://github.com/ggabriel96/alchemista/commit/b87a9071363a0f7b2f5c78afba70ac4038262e61))
* Added is_optional helper function ([`acb80db`](https://github.com/ggabriel96/alchemista/commit/acb80dbb8ed5bb27c20e63240f6d25483debd10c))

Breaking
* minimum required Python version is now 3.8 instead of 3.6 ([`ee267ec`](https://github.com/ggabriel96/alchemista/commit/ee267ec1bf25726137074b514aab0034ec052e19))

Documentation
* **README.md:** Added short explanation of the transform feature ([`7bfa21a`](https://github.com/ggabriel96/alchemista/commit/7bfa21a6a22510fe5023b5ecae13ba66e7fd8ef8))

Fix
* Nullable columns were not generating Optional fields ([`d49f161`](https://github.com/ggabriel96/alchemista/commit/d49f161684e1d2c8563cbec9a1db52d85cffbdd6))

Documentation
* **README.md:** Added short explanation of fields_from ([`5b4daa0`](https://github.com/ggabriel96/alchemista/commit/5b4daa01d643e23d272501ec5cf1b8c7ddf3def3))