Update the Python requirement (#54)

* Update the Python requirement

The newest type hints make the code incompatible with Python <= 3.8, so adjust the requirement accordingly.

* Also update the requirement in pyproject.

* Add pytest as a requirement

README.md

@@ -27,7 +27,7 @@ To see the contents of this python module, check our [Python API docs](https://u
 If you want to build an executable from the Fortran source, head to `src/fortran_src` and run `make`. You can then run the executable with `./uclchem CLOUD input_file.inp` where there examples of input files in the `examples/` directory. We do not suggest users use the code this way unt
 
 ### Prerequisites
-To build UCLCHEM, you'll need gfortran, make and python 3.6+.
+To build UCLCHEM, you'll need gfortran, make and python 3.9+.
 
 To run the python module, you'll need the python modules listed in `requirements.txt`
 

pyproject.toml

@@ -20,9 +20,9 @@ maintainers = [
 {name="Gijs Vermariën", email="[email protected]"}]
 description="A package for the astrochemical modelling of gas-grain chemistries."
 readme = "README.md"
-requires-python = ">=3.8"
+requires-python = ">=3.9"
 license = {text = "MIT License"}
 dependencies = [
-    "pandas", "numpy", "pyyaml", "matplotlib", "seaborn",
+    "pandas", "numpy", "pyyaml", "matplotlib", "seaborn", "pytest"
 ]