Revert "Bump dart-lang/setup-dart from 1.4.0 to 1.5.0 (dart-lang/pubspec_parse#100)" (dart-lang/pubspec_parse#101)

This reverts commit 6789ce31ca88aa65cd737e94ad3234124edd5eac.
diff --git a/pkgs/pubspec_parse/.github/workflows/test-package.yml b/pkgs/pubspec_parse/.github/workflows/test-package.yml
index 44a40de..a099ceb 100644
--- a/pkgs/pubspec_parse/.github/workflows/test-package.yml
+++ b/pkgs/pubspec_parse/.github/workflows/test-package.yml
@@ -23,7 +23,7 @@
         sdk: [dev]
     steps:
       - uses: actions/checkout@8e5e7e5ab8b370d6c329ec480221332ada57f0ab
-      - uses: dart-lang/setup-dart@d6a63dab3335f427404425de0fbfed4686d93c4f
+      - uses: dart-lang/setup-dart@a57a6c04cf7d4840e88432aad6281d1e125f0d46
         with:
           sdk: ${{ matrix.sdk }}
       - id: install
@@ -49,7 +49,7 @@
         sdk: [2.18.0, dev]
     steps:
       - uses: actions/checkout@8e5e7e5ab8b370d6c329ec480221332ada57f0ab
-      - uses: dart-lang/setup-dart@d6a63dab3335f427404425de0fbfed4686d93c4f
+      - uses: dart-lang/setup-dart@a57a6c04cf7d4840e88432aad6281d1e125f0d46
         with:
           sdk: ${{ matrix.sdk }}
       - id: install