(GitHub CI) Bump actions/checkout version in workflows (#1188)

Author: ArjunSharda

.github/workflows/dependabot.yml

@@ -0,0 +1,6 @@
+version: 2
+updates:
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "weekly"

.github/workflows/dockerimage.yml

@@ -13,6 +13,6 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v3
     - name: Build the Docker image
-      run: docker build -f Dockerfile.CompressImages . -t imgbot
+      run: docker build -f Dockerfile.CompressImages . -t imgbot

.github/workflows/test.yml

@@ -13,7 +13,7 @@ jobs:
         dotnet-version: [ '2.1' ]
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - name: Setup .NET Core SDK ${{ matrix.dotnet-version }}
         uses: actions/[email protected]
         with:
@@ -23,4 +23,4 @@ jobs:
       - name: Build
         run: dotnet build --configuration Release --no-restore
       - name: Test
-        run: dotnet test --no-restore --verbosity normal
+        run: dotnet test --no-restore --verbosity normal