dependencies: bump flask-iiif

Did we forget to bump this dependency or was there a larger reason for
keeping it clamped so low? None of the flask-iiif improvements from the past year
have been adopted by InvenioRDM it means.

I will backport this to v12 maint branch once merged as it prevents our instance
from previewing specific medical images.

setup.cfg

@@ -36,7 +36,7 @@ install_requires =
     datacite>=1.1.1,<2.0.0
     dcxml>=0.1.2,<1.0.0
     Faker>=2.0.3
-    flask-iiif>=0.6.2,<1.0.0
+    flask-iiif>=1.0.0,<2.0.0
     ftfy>=4.4.3,<5.0.0
     invenio-administration>=2.0.0,<3.0.0
     invenio-communities>=15.0.0,<16.0.0