Use Git Large File Storage for snapshot images (#1824)

.github/workflows/main.yml

@@ -39,6 +39,8 @@ jobs:
     runs-on: macos-12
     steps:
       - uses: actions/checkout@v2
+        with:
+          lfs: 'true'
       - uses: ./.github/actions/setup
       - name: Test Package
         run: bundle exec rake test:package

README.md

@@ -75,6 +75,13 @@ We always appreciate contributions from the community. To make changes to the pr
  - unit tests and snapshot tests (for iOS, must be run on an iPhone 8 simulator)
  - an Example iOS app that lets you browse and test over 100 sample animations included in the repo
 
+To reduce the size of the repository, snapshot images are stored using [Git Large File Storage](https://git-lfs.github.com/). Before running the snapshot tests, you'll need to install Git LFS:
+
+```bash
+$ brew install git-lfs
+$ git lfs install
+```
+
 All pull requests with new features or bug fixes that affect how animations render should include snapshot test cases that validate the included changes. 
   - To add a new sample animation to the snapshot testing suite, you can add the `.json` file to `Tests/Samples`. Re-run the snapshot tests to generate the new snapshot image files.
   - To update existing snapshots after making changes, you can set `isRecording = true` in `SnapshotTests.swift` and then re-run the snapshot tests.