Merge for v8.4

[raphaelquast]

🌦️ Changes

• You can now add multiple temporary artists with a single call with the following methods:
  (Note that the "layer" kwarg is now keyword-only!)
  • m.BM.add_artist(*artists, layer="my layer")
  • m.BM.add_bg_artist(*artists, layer="my layer")
  • m.cb.<method>.add_temporary_artist(*artists, layer="my layer")
• Minimum supported python version is now python>=3.9

🌳 New

• New convenience method: m.new_subplot() to add an ordinary matpltolib subplot.
• New contextmanager: m.cb.<event-type>.make_artists_temporary() to simplify
  the use of temporary artists in callbacks. Just create your temporary artists within the callback and
  to have them removed on the next <event-type> event (e.g. "click", "pick", "keypress" or "move").
• New WebMap service provided by the city of Vienna (data.wien.gv.at) is accessible via:
  m.add_wms.Austria.Wien_data...
• You can now use pip install eomaps[docs] to install all required dependencies to build the docs
• New convenience methods m.transform_lonlat_to_plot() and m.transform_plot_to_lonlat() that can be used
  to quickly transform coordinates from the plot-reference system to longitude/latitude and vice-versa.

🔨 Fixes

• address deprecation warning for GeoDataFrame.unary_union
• remove python 3.8 from unittests and add python 3.13
• fix m.get_layout reporting figure dimensions as numpy-floats
• fix issues with "always_on_top" flag
• fix issues with numpy v2.x and WebMapService BBox extents
• fix m.add_wms.GEBCO... webmaps
• fix temporary grids are redrawn on fetch-background

[codecov]

Codecov Report

❌ Patch coverage is 66.66667% with 35 lines in your changes missing coverage. Please review.
✅ Project coverage is 75.46%. Comparing base (63c5a3d) to head (9350307).
⚠️ Report is 5 commits behind head on master.

Files with missing lines	Patch %	Lines
eomaps/cb_container.py	50.00%	9 Missing ⚠️
eomaps/eomaps.py	56.25%	7 Missing ⚠️
eomaps/webmap_containers.py	33.33%	6 Missing ⚠️
eomaps/_blit_manager.py	80.00%	5 Missing ⚠️
eomaps/annotation_editor.py	0.00%	3 Missing ⚠️
eomaps/_webmap.py	81.81%	2 Missing ⚠️
eomaps/callbacks.py	75.00%	1 Missing ⚠️
eomaps/colorbar.py	50.00%	1 Missing ⚠️
eomaps/scalebar.py	75.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #267      +/-   ##
==========================================
+ Coverage   75.23%   75.46%   +0.22%     
==========================================
  Files          27       27              
  Lines       11908    11956      +48     
==========================================
+ Hits         8959     9022      +63     
+ Misses       2949     2934      -15     

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