Fix static typing with Matplotlib 3.8 (#8030)

* fix several typing issues with mpl3.8

* fix scatter plot typing and remove funky pyplot import

* fix some more typing errors

* fix some import errors

* undo some typing errors

* fix xylim typing

* add forgotten import

* ignore plotting overloads because None is Hashable

* add whats-new entry

* fix return type of hist

* fix another xylim type

* fix some more xylim types

* change to T_DataArray

* change accessor xylim to tuple

* add missing return types

* fix a typing error only on new mpl

* add unused-ignore to error codes for old mpl

* add more unused-ignore to error codes for old mpl

* replace type: ignore[attr-defined] with assert hasattr

* apply code review suggestions

---------

Co-authored-by: Illviljan <14371165+Illviljan@users.noreply.github.com>

doc/whats-new.rst

@@ -40,6 +40,9 @@ Breaking changes
   extracts and add the indexes from another :py:class:`Coordinates` object
   passed via ``coords`` (:pull:`8107`).
   By `Benoît Bovy <https://github.com/benbovy>`_.
+- Static typing of ``xlim`` and ``ylim`` arguments in plotting functions now must
+  be ``tuple[float, float]`` to align with matplotlib requirements. (:issue:`7802`, :pull:`8030`).
+  By `Michael Niklas <https://github.com/headtr1ck>`_.
 
 Deprecations
 ~~~~~~~~~~~~

xarray/core/options.py

@@ -6,10 +6,8 @@
 from xarray.core.utils import FrozenDict
 
 if TYPE_CHECKING:
-    try:
-        from matplotlib.colors import Colormap
-    except ImportError:
-        Colormap = str
+    from matplotlib.colors import Colormap
+
     Options = Literal[
         "arithmetic_join",
         "cmap_divergent",
@@ -164,11 +162,11 @@ class set_options:
     cmap_divergent : str or matplotlib.colors.Colormap, default: "RdBu_r"
         Colormap to use for divergent data plots. If string, must be
         matplotlib built-in colormap. Can also be a Colormap object
-        (e.g. mpl.cm.magma)
+        (e.g. mpl.colormaps["magma"])
     cmap_sequential : str or matplotlib.colors.Colormap, default: "viridis"
         Colormap to use for nondivergent data plots. If string, must be
         matplotlib built-in colormap. Can also be a Colormap object
-        (e.g. mpl.cm.magma)
+        (e.g. mpl.colormaps["magma"])
     display_expand_attrs : {"default", True, False}
         Whether to expand the attributes section for display of
         ``DataArray`` or ``Dataset`` objects. Can be