Isolate Perseus as optional dependency

pyproject.toml

@@ -25,11 +25,9 @@ dependencies = [
     "pandas",
     "scikit-learn",
     "nvidia-ml-py",
-    "pydantic",
+    "pydantic",  # The `zeus.util.pydantic_v1` compatibility layer allows us to unpin Pydantic in most cases.
     "rich",
     "tyro",
-    "httpx",
-    "aiofiles==22.1.0",
 ]
 dynamic = ["version"]
 
@@ -39,10 +37,11 @@ Homepage = "https://ml.energy/zeus"
 Documentation = "https://ml.energy/zeus"
 
 [project.optional-dependencies]
-perseus = ["fastapi[all]", "lowtime"]
+# One day FastAPI will drop support for Pydantic V1. Then fastapi has to be pinned as well.
+perseus = ["fastapi[all]", "pydantic<2", "lowtime", "aiofiles", "httpx"]
 lint = ["ruff", "black==22.6.0"]
 test = ["pytest==7.3.2", "pytest-mock==3.10.0", "pytest-xdist==3.3.1"]
-dev = ["ruff", "black==22.6.0", "pytest==7.3.2", "pytest-mock==3.10.0", "pytest-xdist==3.3.1"]
+dev = ["zeus-ml[perseus,lint,test]"]
 
 [tool.setuptools.packages.find]
 where = ["."]