enforce py39 min

[ocefpaf]

Should help with #2167

[ocefpaf]

pre-commit.ci autofix

[ocefpaf]

@hansthen I'd love your help with the mypy failure here.

[hansthen]

@hansthen I'd love your help with the mypy failure here.

The issue is upstream in Branca. The offending code returns Element._parent as Element but in Branca that is an object.

I was able to get rid of the error using this:

diff --git a/branca/element.py b/branca/element.py
index 1912aca..ad21bbf 100644
--- a/branca/element.py
+++ b/branca/element.py
@@ -55,7 +55,7 @@ class Element:
         self._name = "Element"
         self._id = hexlify(urandom(16)).decode()
         self._children = OrderedDict()
-        self._parent = None
+        self._parent: Element = None
         self._template_str = template
         self._template_name = template_name

However, Branca does not use much typing so far. Let me check if there is a better way.

[hansthen]

I could not get typing to work without either changing branca or adding # type: ignore line to the offending function.

[hansthen]

I think just disabling typing for this line here is okay. I also removed some unused typing info (in the body of an untyped function) because it triggered a warning.

[ocefpaf]

Thanks! Please merge I'd you are happy with this PR.