Bump actions/checkout from 2 to 3 (#61)

Bumps [actions/checkout](https://github.com/actions/checkout) from 2 to 3.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v2...v3)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

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

.github/workflows/flutter_beta.yml

@@ -13,7 +13,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - uses: subosito/flutter-action@v2.4.0
         with:
           channel: ${{ env.FLUTTER_CHANNEL }}
@@ -25,7 +25,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v3
     - uses: subosito/flutter-action@v2.4.0
       with:
         channel: ${{ env.FLUTTER_CHANNEL }}
@@ -41,7 +41,7 @@ jobs:
         working-directory: example
 
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v3
     - uses: actions/setup-java@v3
       with:
         java-version: '11'
@@ -63,7 +63,7 @@ jobs:
         working-directory: example
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - uses: subosito/flutter-action@v2.4.0
         with:
           channel: ${{ env.FLUTTER_CHANNEL }}
@@ -87,7 +87,7 @@ jobs:
         working-directory: example
 
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v3
     - uses: subosito/flutter-action@v2.4.0
       with:
         channel: ${{ env.FLUTTER_CHANNEL }}

.github/workflows/flutter_ci.yml

@@ -12,7 +12,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - name: Cache Flutter
         uses: actions/cache@v3.0.2
         with:
@@ -30,7 +30,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - name: Cache Flutter
         uses: actions/cache@v3.0.2
         with:
@@ -52,7 +52,7 @@ jobs:
         working-directory: example
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - uses: actions/setup-java@v3
         with:
           java-version: '11'
@@ -80,7 +80,7 @@ jobs:
         working-directory: example
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - name: Cache Flutter
         uses: actions/cache@v3.0.2
         with:
@@ -110,7 +110,7 @@ jobs:
         working-directory: example
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - name: Cache Flutter
         uses: actions/cache@v3.0.2
         with:

.github/workflows/generate_docs.yml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
 
       - uses: subosito/flutter-action@v2.4.0