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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[CLA]: https://cla.developers.google.com/
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[Contributors Guide]:
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experimental/linting_tool/lib/model/profiles_store.dart

@@ -140,7 +140,7 @@ class ProfilesStore extends ChangeNotifier {
     const name = 'analysis_options.yaml';
 
     /// Get file path using file picker.
-    final savePath = await file_selector.getSavePath(
+    final saveLocation = await file_selector.getSaveLocation(
       suggestedName: name,
     );
 
@@ -148,8 +148,8 @@ class ProfilesStore extends ChangeNotifier {
     final file = file_selector.XFile.fromData(data, name: name);
 
     /// Save file to disk if path was provided.
-    if (savePath != null) {
-      await file.saveTo(savePath);
+    if (saveLocation != null) {
+      await file.saveTo(saveLocation.path);
       return true;
     }