Properly handle bug in libdmtx
b20e1dc7 patches a bug in libdmtx where recent versions don't decode the datamatrix.
The bug was reported for pylibdmtx, however it exists upstream and applies to all versions of libdmtx ≥0.7.5, and up to current.
We should:
- Report the bug upstream
- Do a more robust check for its presence than a blank try-catch
- Eventually rely on a patched version of libdmtx