Metaclass bug

[LouisK92]

Redoing PR #254 now first into dev to trigger github actions when merging with main - oups.

Description of changes

• Adjusted class _AxesSubplot to fix metaclass issue Metaclass TypeError #253
  (related: see matplotlib 3.7 compat scverse/scanpy#2414 fixed TypeError: metaclass conflict: matplotlib v3.7.0 is incompatible with scanpy scverse/scanpy#2411)

Relevant code snippets

1. import spapros as sp works again.

import spapros as sp
adata = sp.ut.get_processed_pbmc_data()
selector = sp.se.ProbesetSelector(adata, "celltype", n=30, verbosity=0)
selector.select_probeset()

sp.pl.masked_dotplot(adata,selector)

is not affected.