chore: use hatchling instead of setuptools (#4770)

This swaps out the build backend of pyodide-build for hatchling, which is
simpler and faster.

The difference in the SDists: This removes the zip directories entries,
setup.cfg, and .egg-info directory and contents. It includes the .gitignore,
since hatchling uses that to decide what to include by default.

The difference in the wheel built from the SDist: The useless top_level.txt is
gone and the license is in the licenses directory.

pyodide-build/pyproject.toml

@@ -1,6 +1,6 @@
 [build-system]
-requires = ["setuptools>=61.2"]
-build-backend = "setuptools.build_meta"
+requires = ["hatchling"]
+build-backend = "hatchling.build"
 
 [project]
 name = "pyodide-build"
@@ -71,19 +71,10 @@ deploy = [
     "moto",
 ]
 
-[tool.setuptools]
-package-dir = {"" = "."}
-license-files = ["LICENSE"]
-include-package-data = false
+[tool.hatch]
+version.path = "pyodide_build/__init__.py"
 
-[tool.setuptools.packages.find]
-where = ["."]
-exclude = ["pyodide_build.tests*"]
-namespaces = true
-
-[tool.setuptools.package-data]
-"pyodide_build.tools" = ["*.ini", "*.cross"]
-"pyodide_build.tools.cmake.Modules.Platform" = ["*.cmake"]
-
-[tool.setuptools.dynamic]
-version = {attr = "pyodide_build.__version__"}
+[tool.hatch.build.targets.sdist]
+exclude = [
+    "/pyodide_build/tests",
+]