Switch to flit build backend (#271)

Author: blink1073

.flake8

@@ -0,0 +1,17 @@
+[flake8]
+ignore = E501, W503, E402
+builtins = c, get_config
+exclude =
+    .cache,
+    .github,
+    docs,
+    setup.py
+enable-extensions = G
+extend-ignore =
+    G001, G002, G004, G200, G201, G202,
+    # black adds spaces around ':'
+    E203,
+per-file-ignores =
+    # B011: Do not call assert False since python -O removes these calls
+    # F841 local variable 'foo' is assigned to but never used
+    tests/*: B011, F841

MANIFEST.in

@@ -1,14 +1,77 @@
 [build-system]
-requires = ["jupyter_packaging>=0.9", "jupyter_server"]
-build-backend = "setuptools.build_meta"
+requires = ["flit_core >=3.2,<4"]
+build-backend = "flit_core.buildapi"
+
+[project]
+name = "jupyterlab_server"
+license = { file = "LICENSE" }
+description = "A set of server components for JupyterLab and JupyterLab like applications."
+keywords = ["jupyter", "jupyterlab"]
+classifiers = [
+  "Framework :: Jupyter",
+  "Framework :: Jupyter :: JupyterLab",
+  "Intended Audience :: Developers",
+  "Intended Audience :: Science/Research",
+  "Intended Audience :: System Administrators",
+  "License :: OSI Approved :: BSD License",
+  "Programming Language :: Python",
+  "Programming Language :: Python :: 3 :: Only",
+  "Programming Language :: Python :: 3.7",
+  "Programming Language :: Python :: 3.8",
+  "Programming Language :: Python :: 3.9",
+  "Programming Language :: Python :: 3.10",]
+requires-python = ">=3.7"
+dependencies = [
+  "babel",
+  "importlib_metadata>=3.6;python_version<\"3.10\"",
+  "jinja2>=3.0.3",
+  "json5",
+  "jsonschema>=3.0.1",
+  "jupyter_server>=1.8,<2",
+  "packaging",
+  "requests",
+]
+dynamic = ["version"]
+
+[[project.authors]]
+name = "Jupyter Development Team"
+email = "[email protected]"
+
+[project.readme]
+file = "README.md"
+content-type = "text/markdown"
+
+[project.urls]
+Homepage = "https://jupyterlab-server.readthedocs.io"
+Documentation = "https://jupyterlab-server.readthedocs.io"
+Funding = "https://numfocus.org/donate-to-jupyter"
+Source = "https://github.com/jupyterlab/jupyterlab_server"
+Tracker = "https://github.com/jupyterlab/jupyterlab_server/issues"
+
+[project.optional-dependencies]
+openapi = [
+  "openapi_core>=0.14.2",
+  "ruamel.yaml",
+]
+test = [
+  "codecov",
+  "ipykernel",
+  "jupyter_server[test]",
+  "openapi_core>=0.14.2",
+  "openapi-spec-validator<0.5",
+  "pytest>=5.3.2",
+  "pytest-console-scripts",
+  "pytest-cov",
+  "ruamel.yaml",
+  "strict-rfc3339"
+]
+
+[tool.flit.sdist]
+include = ["tests/"]
 
 [tool.jupyter-releaser]
 skip = ["check-links"]
 
-[tool.check-manifest]
-ignore = ["tbump.toml", ".*", "*.yml", "docs/source/api/app-config.rst", "docs/source/changelog.md"]
-ignore-bad-ideas = ["tests/translations/**/*.mo"]
-
 [tool.tbump.version]
 current = "2.13.0"
 regex = '''