Migrated the metadata into PEP 621-compliant pyproject.toml (#138)

* Move the metadata from `setup.py` into `setup.cfg`.
Added `pyproject.toml`.
Removed `setup.py` - it is no longer needed.
Got rid of tests erroroneously finding their way into the wheel.

* Started populating version automatically from git tags using `setuptools_scm`.

* Migrated the metadata into `PEP 621`-compliant `pyproject.toml`, got rid of `setup.cfg`.

* test build in develop and pull requests

* use static version instead of dynamic git tag info

---------

Co-authored-by: KOLANICH <kolan_n@mail.ru>

.github/workflows/python-publish.yml

@@ -21,11 +21,11 @@ jobs:
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip
-        pip install setuptools wheel twine
+        pip install --upgrade setuptools setuptools_scm wheel build twine
     - name: Build and publish
       env:
         TWINE_USERNAME: ${{ secrets.PYPI_USERNAME }}
         TWINE_PASSWORD: ${{ secrets.PYPI_PASSWORD }}
       run: |
-        python setup.py sdist bdist_wheel
+        python -m build -nwsx .
         twine upload dist/*