Standardize CI action (#62)

Author: kevmoo

.github/workflows/build.yaml

@@ -21,7 +21,7 @@ jobs:
         sdk: [dev]
     steps:
     - uses: actions/checkout@v2
-    - uses: dart-lang/setup-dart@v1
+    - uses: dart-lang/setup-dart@v1.0
       with:
         sdk: ${{ matrix.sdk }}
     - id: install
@@ -44,7 +44,7 @@ jobs:
         sdk: [2.12.0, dev]
     steps:
     - uses: actions/checkout@v2
-    - uses: dart-lang/setup-dart@v1
+    - uses: dart-lang/setup-dart@v1.0
       with:
         sdk: ${{ matrix.sdk }}
     - id: install