[mkdocs] breaking examples with Python 3.13.3 on MacOS

At 36bd491a9 I get the following breaks from make examples-force in these files:

• doc/python/graphing-multiple-chart-types.md
• doc/python/hexbin-mapbox.md
• doc/python/ml-tsne-umap-projections.md
• doc/python/orca-management.md
• doc/python/px-arguments.md
• doc/python/sankey-diagram.md
• doc/python/scatter-plots-on-maps.md
• doc/python/tile-county-choropleth.md
• doc/python/tile-map-layers.md
• doc/python/tile-scatter-maps.md

uv run bin/run_markdown.py --outdir pages --htmldir pages/examples --inline --verbose 2 doc/python/graphing-multiple-chart-types.md
Processing doc/python/graphing-multiple-chart-types.md...
- Found 5 code blocks
- Executing block 0/5
- Executing block 1/5
- Executing block 2/5
- Executing block 3/5
  - Warning: block 3 had an error
- Executing block 4/5

uv run bin/run_markdown.py --outdir pages --htmldir pages/examples --inline --verbose 2 doc/python/hexbin-mapbox.md
Processing doc/python/hexbin-mapbox.md...
- Found 6 code blocks
- Executing block 0/6
  - Warning: block 0 had an error
- Executing block 1/6
  - Warning: block 1 had an error
- Executing block 2/6
  - Warning: block 2 had an error
- Executing block 3/6
  - Warning: block 3 had an error
- Executing block 4/6
  - Warning: block 4 had an error
- Executing block 5/6
  - Warning: block 5 had an error

uv run bin/run_markdown.py --outdir pages --htmldir pages/examples --inline --verbose 2 doc/python/ml-tsne-umap-projections.md
Processing doc/python/ml-tsne-umap-projections.md...
- Found 5 code blocks
- Executing block 0/5
- Executing block 1/5
- Executing block 2/5
- Executing block 3/5
  - Warning: block 3 had an error
- Executing block 4/5
  - Warning: block 4 had an error

uv run bin/run_markdown.py --outdir pages --htmldir pages/examples --inline --verbose 2 doc/python/orca-management.md
Processing doc/python/orca-management.md...
- Found 9 code blocks
- Executing block 0/9
- Executing block 1/9
- Executing block 2/9
- Executing block 3/9
  - Warning: block 3 had an error
- Executing block 4/9
- Executing block 5/9
  - Warning: block 5 had an error
- Executing block 6/9
- Executing block 7/9
  - Warning: block 7 had an error
- Executing block 8/9

uv run bin/run_markdown.py --outdir pages --htmldir pages/examples --inline --verbose 2 doc/python/px-arguments.md
Processing doc/python/px-arguments.md...
- Found 18 code blocks
- Executing block 0/18
  - Warning: block 0 had an error
- Executing block 1/18
  - Warning: block 1 had an error
- Executing block 2/18
- Executing block 3/18
- Executing block 4/18
- Executing block 5/18
- Executing block 6/18
- Executing block 7/18
- Executing block 8/18
- Executing block 9/18
- Executing block 10/18
- Executing block 11/18
- Executing block 12/18
- Executing block 13/18
- Executing block 14/18
- Executing block 15/18
- Executing block 16/18
- Executing block 17/18

uv run bin/run_markdown.py --outdir pages --htmldir pages/examples --inline --verbose 2 doc/python/sankey-diagram.md
Processing doc/python/sankey-diagram.md...
- Found 10 code blocks
- Executing block 0/10
- Executing block 1/10
  - Warning: block 1 had an error
- Executing block 2/10
- Executing block 3/10
- Executing block 4/10
- Executing block 5/10
- Executing block 6/10
- Executing block 7/10
- Executing block 8/10
- Executing block 9/10

uv run bin/run_markdown.py --outdir pages --htmldir pages/examples --inline --verbose 2 doc/python/scatter-plots-on-maps.md
Processing doc/python/scatter-plots-on-maps.md...
- Found 6 code blocks
- Executing block 0/6
- Executing block 1/6
- Executing block 2/6
  - Warning: block 2 had an error
- Executing block 3/6
- Executing block 4/6
- Executing block 5/6

uv run bin/run_markdown.py --outdir pages --htmldir pages/examples --inline --verbose 2 doc/python/tile-county-choropleth.md
Processing doc/python/tile-county-choropleth.md...
- Found 10 code blocks
- Executing block 0/10
- Executing block 1/10
- Executing block 2/10
- Executing block 3/10
- Executing block 4/10
- Executing block 5/10
- Executing block 6/10
- Executing block 7/10
- Executing block 8/10
- Executing block 9/10
  - Warning: block 9 had an error

uv run bin/run_markdown.py --outdir pages --htmldir pages/examples --inline --verbose 2 doc/python/tile-map-layers.md
Processing doc/python/tile-map-layers.md...
- Found 8 code blocks
- Executing block 0/8
- Executing block 1/8
- Executing block 2/8
- Executing block 3/8
- Executing block 4/8
- Executing block 5/8
- Executing block 6/8
  - Warning: block 6 had an error
- Executing block 7/8

uv run bin/run_markdown.py --outdir pages --htmldir pages/examples --inline --verbose 2 doc/python/tile-scatter-maps.md
Processing doc/python/tile-scatter-maps.md...
- Found 11 code blocks
- Executing block 0/11
- Executing block 1/11
  - Warning: block 1 had an error
- Executing block 2/11
- Executing block 3/11
- Executing block 4/11
- Executing block 5/11
- Executing block 6/11
- Executing block 7/11
- Executing block 8/11
- Executing block 9/11
  - Warning: block 9 had an error
- Executing block 10/11
  - Warning: block 10 had an error

Start by rerunning make examples-force, or the reported uv run bin/run_markdown.py command, through bin/run_markdown.py. Check the failing blocks in doc/python/graphing-multiple-chart-types.md, hexbin-mapbox.md, ml-tsne-umap-projections.md, orca-management.md, px-arguments.md, sankey-diagram.md, scatter-plots-on-maps.md, tile-county-choropleth.md, tile-map-layers.md, and tile-scatter-maps.md; done means the listed examples execute without warnings.