Update workflow to use SDK 3.7

Author: lrhn

.github/workflows/package_config.yaml

@@ -54,7 +54,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-latest, windows-latest]
-        sdk: [3.4, dev]
+        sdk: [3.7, dev]
     steps:
       - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683
       - uses: dart-lang/setup-dart@e630b99d28a3b71860378cafdc2a067c71107f94