fix: Set Python version to 3.10

[alexanderroidl]

By default a Python version which is not compatible to currently used syntax is being installed:

❯ pipenv install
(...) ✅
❯ pipenv run python --version
Python 3.9.18
❯ pipenv run python flathunt.py
Traceback (most recent call last):
File "/Users/alexander.roidl/Private/flathunter/flathunt.py", line 13, in <module>
from flathunter.hunter import Hunter
File "/Users/alexander.roidl/Private/flathunter/flathunter/hunter.py", line 13, in <module>
class Hunter:
File "/Users/alexander.roidl/Private/flathunter/flathunter/hunter.py", line 39, in Hunter
def hunt_flats(self, max_pages: None|int = None):
TypeError: unsupported operand type(s) for |: 'NoneType' and 'type'

hunter.py:39:
def hunt_flats(self, max_pages: None|int = None):

flathunter/flathunter/hunter.py

Line 39 in a8b473d

def hunt_flats(self, max_pages: None|int = None):

This so called "union-type operator" was only introduced in Python 3.10:
https://docs.python.org/3/whatsnew/3.10.html#pep-604-new-type-union-operator

Therefore I changed the Pipfile accordingly. 😊

---

[codders]

I guess this is a bit more complicated. I set the version at 3 so that I could test with both 3.9 and 3.10 (and 3.11). The CI tests are running 3.10 and 3.11, which is why we don't see failures for this in CI.

As far as I know, Pipfile does not have support for saying Python version >= 3.x - we either pin to a specific point version, or we let the system install whatever python 3 it can find.

So you think we should just force 3.10 and not support any other version (until we bump to 3.11)? I don't know what the best practice here is.

[alexanderroidl]

I guess this is a bit more complicated. I set the version at 3 so that I could test with both 3.9 and 3.10 (and 3.11). The CI tests are running 3.10 and 3.11, which is why we don't see failures for this in CI.

As far as I know, Pipfile does not have support for saying Python version >= 3.x - we either pin to a specific point version, or we let the system install whatever python 3 it can find.

So you think we should just force 3.10 and not support any other version (until we bump to 3.11)? I don't know what the best practice here is.

As far as I'm concerned we stopped supporting versions before 3.10 in September:
1409897

So we do not need to run tests on 3.9 anyways.

The source code is literally incompatible with anything before 3.10, therefore it needs to be forced. The Pipfile supports this as well!