Update start-exercise workflow to v0.8.1 and checkout main branch

Co-authored-by: FidelusAleksander <63016446+FidelusAleksander@users.noreply.github.com>

Author: Copilot

.github/workflows/0-start-exercise.yml

@@ -18,7 +18,7 @@ jobs:
     if: |
       !github.event.repository.is_template
     name: Start Exercise
-    uses: skills/exercise-toolkit/.github/workflows/start-exercise.yml@v0.8.0
+    uses: skills/exercise-toolkit/.github/workflows/start-exercise.yml@v0.8.1
     with:
       exercise-title: "Code with Codespaces"
       intro-message: "Let's create a pre-configured environment to simplify development!"
@@ -33,6 +33,8 @@ jobs:
     steps:
       - name: Checkout
         uses: actions/checkout@v4
+        with:
+          ref: main
 
       - name: Get response templates
         uses: actions/checkout@v4