Use isort to reorder python imports

reorder-python-imports is hard to set up correctly.

isort is a lot simpler to set to set up it locally, and is kinda
becoming the standard in the python world.

The import style remains the same, and is tweaked to minimise conflicts.

.pre-commit-config.yaml

@@ -17,7 +17,8 @@ repos:
     rev: "21.6b0"
     hooks:
       - id: black
-  - repo: https://github.com/asottile/reorder_python_imports
-    rev: v2.5.0
+  - repo: https://github.com/pycqa/isort
+    rev: 5.8.0
     hooks:
-    -   id: reorder-python-imports
+      - id: isort
+        name: isort (python)

setup.cfg

@@ -21,3 +21,6 @@ extend-ignore =
 max-line-length = 88
 exclude = .eggs,build
 import-order-style = smarkets
+
+[isort]
+force_single_line=true