Add some Ruff ignores, enable it in GH Actions

It's only reporting errors for now, I'll make it mandatory after having
fixed or ignore a lot of errors :)

.github/workflows/build.yaml

@@ -25,6 +25,9 @@ jobs:
           sudo apt install -y graphviz graphviz-dev python3-dev
           python -m pip install poetry
           poetry install --all-extras
+      - name: Lint with Ruff
+        run: poetry run ruff
+        continue-on-error: true  # temporary, until we've updated the codebase to Ruff's standards
       - name: Typecheck with mypy
         run: poetry run mypy
       - name: Test with pytest

server/pyproject.toml

@@ -81,6 +81,11 @@ markers = [
 [tool.ruff]
 line-length = 79
 indent-width = 4
+target-version = "py38"
+exclude = [
+	".git",
+	"migrations",
+]
 
 [tool.ruff.format]
 quote-style = "double"
@@ -129,10 +134,23 @@ ignore = [
 	"ANN102",   # type annotation for @classmethod first argument
 	"ISC001",   # conflict w/ formatter, see https://github.com/astral-sh/ruff/issues/8272
 	"PLC0415",  # forbids dynamic imports
+	"PT006",    # forbids comma-separated string for @pytest.mark.parametrize names
+	"PT007",    # forbids non-list types for @pytest.mark.parametrize values
+	"RUF001",   # complains about Unicode typography in strings
+	"RUF002",   # complains about Unicode typography in docstrings
 	"RUF200",   # requires a name for projects
 	"TRY003",   # complains about simple ValueError messages
 ]
 
 [tool.ruff.lint.isort]
 # Two blank lines after the imports.
 lines-after-imports = 2
+
+[tool.ruff.lint.per-file-ignores]
+"tests/*" = [
+	"ANN001",  # missing function argument annotation
+	"ANN201",  # missing return type annotation
+	"ARG001",  # unused function argument (e.g. require-only fixtures)
+	"INP001",  # implicit namespace package
+	"S101",    # use of assert
+]

server/test.sh

@@ -1,3 +1,3 @@
 #!/bin/sh
 
-poetry run sh -c 'ruff check && mypy && mypy tests && pytest && dearmep check translations'
+poetry run sh -c 'ruff check; mypy && mypy tests && pytest && dearmep check translations'