dogfood the new setup-dart action (#25)

diff --git a/.github/workflows/unified_analytics.yml b/.github/workflows/unified_analytics.yml
index 88d4c4a..4d50d34 100644
--- a/.github/workflows/unified_analytics.yml
+++ b/.github/workflows/unified_analytics.yml
@@ -29,7 +29,7 @@
             run-tests: true
     steps:
       - uses: actions/checkout@ac593985615ec2ede58e132d2e21d2b1cbd6127c
-      - uses: dart-lang/setup-dart@a57a6c04cf7d4840e88432aad6281d1e125f0d46
+      - uses: dart-lang/setup-dart@929ed5f8bae55086c6fac456ba5acb9763c9e3e2
         with:
           sdk: ${{matrix.sdk}}