Fix commit hash gallery (#60507)

https://github.com/flutter/gallery/commit/0c5ec2f285c1ec30b2ed15194bc8de755654a590 does not live on any branch.

This makes `pub get` in the macrobenchmarks folder.

```
$ git rev-list --max-count=100 0c5ec2f285c1ec30b2ed15194bc8de755654a590
fatal: bad object 0c5ec2f285c1ec30b2ed15194bc8de755654a590
```

Updated to the same commit on the master branch: https://github.com/flutter/gallery/commit/d00362e6bdd0f9b30bba337c358b9e4a6e4ca950.