Fix bug raised by example notebooks

[rwood-97]

Summary

Need to drop other geometry columns when running gdf.explore().
Should fix broken tests on https://github.com/maps-as-data/MapReader-examples

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Flag	Coverage Δ
unittests	77.89% <ø> (-0.13%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
mapreader/spot_text/runner_base.py	80.76% <ø> (ø)
setup.py	0.00% <ø> (ø)

... and 2 files with indirect coverage changes

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