Bump dart-lang/setup-dart from 1.5.1 to 1.6.0 (#289)

Bumps [dart-lang/setup-dart](https://github.com/dart-lang/setup-dart) from 1.5.1 to 1.6.0.
- [Release notes](https://github.com/dart-lang/setup-dart/releases)
- [Changelog](https://github.com/dart-lang/setup-dart/blob/main/CHANGELOG.md)
- [Commits](dart-lang/setup-dart@8a4b97e...b64355a)

---
updated-dependencies:
- dependency-name: dart-lang/setup-dart
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

.github/workflows/ci.yaml

@@ -21,7 +21,7 @@ jobs:
         sdk: [dev]
     steps:
     - uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11
-    - uses: dart-lang/setup-dart@8a4b97ea2017cc079571daec46542f76189836b1
+    - uses: dart-lang/setup-dart@b64355ae6ca0b5d484f0106a033dd1388965d06d
       with:
         sdk: ${{ matrix.sdk }}
     - id: install
@@ -43,7 +43,7 @@ jobs:
         sdk: [3.0.0, stable, dev]
     steps:
     - uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11
-    - uses: dart-lang/setup-dart@8a4b97ea2017cc079571daec46542f76189836b1
+    - uses: dart-lang/setup-dart@b64355ae6ca0b5d484f0106a033dd1388965d06d
       with:
         sdk: ${{ matrix.sdk }}
     - uses: nanasess/setup-chromedriver@e66222fd7ec9c46b83cc837781ce6930b5d95f90
@@ -69,7 +69,7 @@ jobs:
         sdk: [3.0.0, stable, dev]
     steps:
     - uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11
-    - uses: dart-lang/setup-dart@8a4b97ea2017cc079571daec46542f76189836b1
+    - uses: dart-lang/setup-dart@b64355ae6ca0b5d484f0106a033dd1388965d06d
       with:
         sdk: ${{ matrix.sdk }}
     - uses: browser-actions/setup-firefox@latest