Force Python version (3.12) for local linting

1) Force Python version (3.12) for local linting (GH CI already enforces Python >=3.10)
   This fixes
   "sourcefinder/config.py:96: error: invalid syntax  [syntax]
        match get_origin(type_):
               ^
   "
   locally, i.e. on my machine, which will pick Python 3.8.13.

2) PEP 8 compliance.

Author: HannoSpreeuw

pyproject.toml

@@ -71,6 +71,7 @@ extra-dependencies = [
 
 [tool.hatch.envs.lint]
 detached = true
+python = "3.12"
 dependencies = [
     "black",
     "flake8",
@@ -80,7 +81,8 @@ dependencies = [
 
 [tool.pytest.ini_options]
 testpaths = ["test"]
-addopts = ["--import-mode=importlib", "--cov=sourcefinder", "-q", "-ra", "-n=logical", "--dist=worksteal", "--cov-config=test/.coveragerc"]
+addopts = ["--import-mode=importlib", "--cov=sourcefinder", "-q", "-ra",
+           "-n=logical", "--dist=worksteal", "--cov-config=test/.coveragerc"]
 
 [tool.black]
 include = '\.pyi?$'