Bump dart-lang/setup-dart from 1.5.1 to 1.6.0 (#680)

Author: dependabot[bot]

.github/workflows/dart.yml

@@ -19,7 +19,7 @@ jobs:
         sdk: [3.0.0, dev]
     steps:
       - uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11
-      - uses: dart-lang/setup-dart@8a4b97ea2017cc079571daec46542f76189836b1
+      - uses: dart-lang/setup-dart@b64355ae6ca0b5d484f0106a033dd1388965d06d
         with:
           sdk: ${{ matrix.sdk }}
       - name: Report version
@@ -71,7 +71,7 @@ jobs:
             platform: chrome
     steps:
       - uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11
-      - uses: dart-lang/setup-dart@8a4b97ea2017cc079571daec46542f76189836b1
+      - uses: dart-lang/setup-dart@b64355ae6ca0b5d484f0106a033dd1388965d06d
         with:
           sdk: ${{ matrix.sdk }}
       - name: Report version