olive-editor: fix build of pinned openimageio

- add `override` to pinned `openimageio` with `fmt_10`, it does not
build with new default `fmt_11`

Fixes build failure of pinned `openimageio`:
```
CMake Error at src/cmake/modules/Findfmt.cmake:19 (string):
  string sub-command REGEX, mode MATCHALL needs at least 5 arguments total to
  command.
Call Stack (most recent call first):
  src/cmake/externalpackages.cmake:325 (find_package)
  src/cmake/externalpackages.cmake:354 (find_or_download_fmt)
  CMakeLists.txt:166 (include)
```

pkgs/by-name/ol/olive-editor/package.nix

@@ -14,12 +14,13 @@
   portaudio,
   imath,
   qt6,
+  fmt_10,
 }:
 
 let
   # https://github.com/olive-editor/olive/issues/2284
   # we patch support for 2.3+, but 2.5 fails
-  openimageio' = openimageio.overrideAttrs (old: rec {
+  openimageio' = (openimageio.override { fmt = fmt_10; }).overrideAttrs (old: rec {
     version = "2.4.15.0";
     src = (
       old.src.override {