Inkex-bh

- `hide_rats.py`: Fix unstyled guide-layer rectangles. (Bug introduced in 1.0.1.)

Fix for Inkscape 1.4.

- Fix `hide_rats.py` for changes in etree API introduced with Inkscape 1.4

- Drop support for python 3.7. Since we only support Inkscape>=1.0
and inkscape 1.0 shipped with python 3.8 this should not cause
issues.

- Test under python 3.12 and 3.13.

- Test under inkex 1.4.0


style

- Use ruff rather than black, flake8, etc. for style linting

create-inset

- Fix to work when there are visible clones of layers with hidden parents. ([2])

[2]: https://github.com/barnhunt/inkex-bh/issues/2

update-symbols

- Only skip symbol sets if they contain a symbol id that conflicts
with an already scanned symbol set. Standard-scale (48:1) symbols
sets are loaded first, so this results in skipping non-standard
symbol sets, but *only* if they contain conflicting symbol ids.
Previously, we just ignored all non-standard symbol sets.

(Until recently, bale sets for non-standard scales (e.g. 60:1) used
the same symbol ids as the standard scale (48:1) sets. As of
`bh-symbols==1.0.0rc5`, all symbols now have globally unique ids.)

- Do not update unchanged symbols.

- Add `dry-run` option to report which symbols would be updated.

- Report the currently installed version of [bh-symbols].

- Added new *update-symbols* extension to update the symbol definitions
in a drawing to those in the installed version of the [bh-symbols] symbol
library.

**NOTE** The *update symbols* operation, if it goes badly, has the
capability to significantly mangle the drawing. Make sure you have
a back-up copy of the drawing before running the extension.

[bh-symbols]: https://github.com/barnhunt/bh-symbols

Refactor

- Use helpers provided by `inkex.command` (rather than calling
`subprocess.run` directly) to run Inkscape (and optipng) from the
*create-inset* extension.

Testing

- Add integration test for the *create-inset* extension. This checks
that the extension can be invoked from Inkscape's batch mode.

- Omit use of virtual environment in `test_run_module_in_installed_extensions`.