desktop_photo_search: getSavePath is deprecated (#1910)

This PR fixes a [CI
breakage](https://github.com/flutter/samples/actions/runs/5362518576/jobs/9729453534):

```console
Analyzing fluent_ui...

   info - lib/src/widgets/unsplash_search_content.dart:51:38 - 'getSavePath' is deprecated and shouldn't be used. Use getSaveLocation instead. Try replacing the use of the deprecated member with the replacement. - deprecated_member_use

1 issue found.
Error: Process completed with exit code 1.
```

## Pre-launch Checklist

- [x] I read the [Flutter Style Guide] _recently_, and have followed its
advice.
- [x] I signed the [CLA].
- [x] I read the [Contributors Guide].
- [x] I updated/added relevant documentation (doc comments with `///`).
- [x] All existing and new tests are passing.

If you need help, consider asking for advice on the #hackers-devrel
channel on [Discord].

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[Contributors Guide]:
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desktop_photo_search/fluent_ui/lib/src/widgets/unsplash_search_content.dart

@@ -48,7 +48,7 @@ class _UnsplashSearchContentState extends State<UnsplashSearchContent> {
             ? PhotoDetails(
                 photo: photoSearchModel.selectedPhoto!,
                 onPhotoSave: (photo) async {
-                  final path = await getSavePath(
+                  final saveLocation = await getSaveLocation(
                     suggestedName: '${photo.id}.jpg',
                     acceptedTypeGroups: [
                       const XTypeGroup(
@@ -58,12 +58,12 @@ class _UnsplashSearchContentState extends State<UnsplashSearchContent> {
                       ),
                     ],
                   );
-                  if (path != null) {
+                  if (saveLocation != null) {
                     final fileData =
                         await photoSearchModel.download(photo: photo);
                     final photoFile =
                         XFile.fromData(fileData, mimeType: 'image/jpeg');
-                    await photoFile.saveTo(path);
+                    await photoFile.saveTo(saveLocation.path);
                   }
                 },
               )