List psutil as a dependency in pyproject.toml

Running tests in parallel with `lit` requires psutil, so add it to the dev
dependencies. While at it also set the required fields in the [project] to
make it easy to use `uv`.

Assisted-by: Gemini CLI

Pull Request: https://github.com/llvm/llvm-project/pull/194285

pyproject.toml

@@ -1,3 +1,20 @@
+[build-system]
+requires = ["hatchling"]
+build-backend = "hatchling.build"
+
+[project]
+name = "LLVM"
+dynamic = ["version"]
+requires-python = ">=3.8"
+
+[tool.hatch.version]
+source = "code"
+path = "llvm/utils/lit/lit/__init__.py"
+expression = "__version__"
+
+[tool.uv]
+package = false
+
 [tool.black]
 extend-exclude = '''
 (
@@ -9,3 +26,8 @@ extend-exclude = '''
 executionEnvironments = [
   { root = "lldb/packages/Python", pythonVersion = "3.8" }
 ]
+
+[dependency-groups]
+dev = [
+    "psutil>=7.2.2",
+]