Update subosito/flutter-action action to v2 (#162)

Co-authored-by: Renovate Bot <bot@renovateapp.com>

Author: renovate[bot]

.github/workflows/feedback.yml

@@ -25,7 +25,7 @@ jobs:
         with:
           java-version: '12.x'
           distribution: 'adopt'
-      - uses: subosito/flutter-action@v1
+      - uses: subosito/flutter-action@v2
         with:
           channel: 'stable'
       - run: flutter pub get
@@ -53,7 +53,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     steps:
       - uses: actions/checkout@v2
-      - uses: subosito/flutter-action@v1
+      - uses: subosito/flutter-action@v2
         with:
           channel: ${{ matrix.flutter_channel }}
       - working-directory: feedback/example

.github/workflows/gitlab.yml

@@ -24,7 +24,7 @@ jobs:
         with:
           java-version: '12.x'
           distribution: 'adopt'
-      - uses: subosito/flutter-action@v1
+      - uses: subosito/flutter-action@v2
         with:
           channel: 'stable'
       - run: flutter pub get

.github/workflows/sentry.yml

@@ -24,7 +24,7 @@ jobs:
         with:
           java-version: '12.x'
           distribution: 'adopt'
-      - uses: subosito/flutter-action@v1
+      - uses: subosito/flutter-action@v2
         with:
           channel: 'stable'
       - run: flutter pub get

.github/workflows/web-example.yml

@@ -10,7 +10,7 @@ jobs:
 
     steps:
       - uses: actions/checkout@v2
-      - uses: subosito/flutter-action@v1
+      - uses: subosito/flutter-action@v2
       - uses: bluefireteam/flutter-gh-pages@v7
         with:
           workingDir: feedback/example