libopenexr-3-1-30 and libopenexr-3-4-33 (should) contain orthogonal sets
of files, and are therefore fundamentally co-installable.

it is important to keep this working at least for the time being,
because the version of gmic packaged in debian is totally outdated,
while the upstream packages are for debian stable and therefore depend
on libopenexr-3-1-30.

the libopenexr-3-1-30 package was briefly broken by actually containing
the libopenexr-3-4-33 libraries. the "Breaks: libopenexr-3-1-30 (<
3.4.6+ds-3)" stanza in the new libopenexr-3-4-33 package is presumably
meant to rectify the situation, but is actually wrong. it should be
"Replaces: libopenexr-3-1-30 (>= 3.4.6+ds-1)", to exclude only the
actually broken package versions, without preventing co-installability
with the correct older versions; the Breaks stanzas are probably not
necessary at all.