restore workflow dependency to master version (#472)

Author: jaeopt

.github/workflows/swift.yml

@@ -47,9 +47,7 @@ jobs:
 
   unittests: 
     if: "${{ github.event.inputs.PREP == '' && github.event.inputs.RELEASE == '' }}" 
-    # restore back to master after merging.
-    #uses: optimizely/swift-sdk/.github/workflows/unit_tests.yml@master
-    uses: optimizely/swift-sdk/.github/workflows/unit_tests.yml@jae/ats-timeout
+    uses: optimizely/swift-sdk/.github/workflows/unit_tests.yml@master
 
   prepare_for_release:
     runs-on: macos-12