fix: Remove coverage from blog post validation workflow

Pytest was failing due to missing coverage tools. Using --no-cov flag
to disable coverage for this specific validation workflow.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: rolfedh

.github/workflows/validate-blog-posts.yml

@@ -41,7 +41,7 @@ jobs:
       - name: Run blog post validation tests
         run: |
           echo "🔍 Running blog post validation tests..."
-          python -m pytest tests/test_blog_post_validation.py -v
+          python -m pytest tests/test_blog_post_validation.py -v --no-cov
       
       - name: Run standalone validation check
         run: |