Update GitHub Actions workflow to improve script checking

Modify tests.yml to:
- Include additional scripts in chmod and shellcheck commands
- Add -x flag to shellcheck for more comprehensive linting
- Ensure all context-related scripts are properly checked

Author: vgrichina

.github/workflows/tests.yml

@@ -23,7 +23,7 @@ jobs:
     
     - name: Make scripts executable
       run: |
-        chmod +x context
+        chmod +x context git-context apply-md
         chmod +x test/test_runner.sh
         chmod +x test/unit/test_*.sh
     
@@ -41,10 +41,10 @@ jobs:
       run: |
         sudo apt-get update
         sudo apt-get install -y shellcheck
-        shellcheck context
-        shellcheck test/test_runner.sh
-        shellcheck test/test_utils.sh
-        shellcheck test/unit/test_*.sh
+        shellcheck -x context git-context apply-md
+        shellcheck -x test/test_runner.sh
+        shellcheck -x test/test_utils.sh
+        shellcheck -x test/unit/test_*.sh
 
   compatibility:
     runs-on: ${{ matrix.os }}