ExtLibs/Mavlink/pymavlink/generator/lib should be replaced with Python 3 compatible code

The following files all contain ___Python 3 SyntaxErrors___ and should be replaced with current upstream versions.

ExtLibs/Mavlink/pymavlink/generator/lib/genxmlif/__init__.py \
ExtLibs/Mavlink/pymavlink/generator/lib/genxmlif/xmlif4Dom.py \
ExtLibs/Mavlink/pymavlink/generator/lib/genxmlif/xmlifApi.py \
ExtLibs/Mavlink/pymavlink/generator/lib/genxmlif/xmlifDom.py \
ExtLibs/Mavlink/pymavlink/generator/lib/genxmlif/xmlifElementTree.py \
ExtLibs/Mavlink/pymavlink/generator/lib/genxmlif/xmlifMinidom.py \
ExtLibs/Mavlink/pymavlink/generator/lib/genxmlif/xmlifUtils.py \
ExtLibs/Mavlink/pymavlink/generator/lib/genxmlif/xmliftest.py \
ExtLibs/Mavlink/pymavlink/generator/lib/minixsv/minixsvWrapper.py \
ExtLibs/Mavlink/pymavlink/generator/lib/minixsv/pyxsval.py \
ExtLibs/Mavlink/pymavlink/generator/lib/minixsv/xsvalBase.py \
ExtLibs/Mavlink/pymavlink/generator/lib/minixsv/xsvalErrorHandler.py \
ExtLibs/Mavlink/pymavlink/generator/lib/minixsv/xsvalSchema.py \
ExtLibs/Mavlink/pymavlink/generator/lib/minixsv/xsvalSimpleTypes.py \
ExtLibs/Mavlink/pymavlink/generator/lib/minixsv/xsvalUtils.py

% [`ruff check | grep ExtLibs | grep SyntaxError`](https://docs.astral.sh/ruff)

Run `ruff check | grep ExtLibs | grep SyntaxError` first, then inspect the listed files under `ExtLibs/Mavlink/pymavlink/generator/lib/genxmlif` and `minixsv`. Compare them with the current upstream versions and replace the incompatible files; done means the listed Python files no longer produce Python 3 SyntaxErrors.

Written by the indexing model from the issue text.