Bump Libraw to 0.21.4 to support Nikon Z8 NIF files

[cyprian]

Now the 0.25.0 depends on libraw 0.21.3 which does not read our NIF files from Nikon Z8, but libraw 0.21.4 does.
Can you please update the dependency?

Thank you.

[letmaik]

Sure, are you happy to contribute a PR? Should be just bumping the submodule and the rawpy version number.

[cyprian]

Done, please review.

[kmilos]

but libraw 0.21.4 does

Er, while the bump is welcome (some CVEs addressed by 0.21.4), there should in theory be no difference in new camera model support from 0.21.3 to 0.21.4 (as seen in the submodule diff).

[channingsugar]

Hi, I still can't read Nikon Z8 NEF files after upgrading to 0.21.4, has this problem been fixed?

[kmilos]

As mentioned above, LibRaw 0.21.4 does not support HE NEF files, nor recent Nikon models like the Z 8 (i.e. any model after Z 9).