Spark-map

In this release we replaced all instances of simple python annotations of lists (like `list[str]`) by their counterparts of the `typing` python package (like `List[str]`).

We did this, because the simple python annotations are a feature available only on very modern python runtimes. This means that, on previous versions of the `spark_map` package, you would get an error while trying to import the package on more old python runtimes.

This change to the `typing` package fix this issue, and makes the spark_map package available to older python runtimes as well, whitout changing anything on the functionality.

This release fix an important issue on the build process of package. Basically, the `setuptools` could not find the source code of the package during the build process of the project. As consequence, the source code (`.py` files) of the package were not included in the distribution files of the package, and, as a consequence, the package could be installed, but not imported to the python session.

This release fix this issue, by changing the folder structure of the package, and adding a couple more options to the `pyproject.toml` file to help `setuptools` to find the source code and included it correctly in the compiled archives of the project.

The version 0.2.6 of the package had an error during the building of the weel of the package. This error occur during the installation process with `pip`.

This release includes a few tweaks to `project.toml` and `setup.py` to fix this instalation error. To fix this error, we included some python packages used during the setup of the package, as dependencies, or as "required packages" to build the package.

Release of the first version of `spark_map` lauched to PyPI. The page of this specific release in PyPI is available at [this link](https://pypi.org/project/spark-map/0.2.6/);

Several improvements in documentation, package strucuture, and the introduction of automated workflows to run unit test across the package were introduced from the last release (v.0.2.1);