graphics/py-fiona: Update to 1.8.18

• The precision option of transform has been fixed for the case of GeometryCollections.
• Added missing --co (creation) option to fio-load.
• If the certifi package can be imported, its certificate store location will be passed to GDAL during import of fiona._env unless CURL_CA_BUNDLE is already set.
• Warn when feature fields named "" are found.

Reported by: portscout