Fix Poetry install command: replace --no-dev with --only=main

Author: orlandocloss

.github/workflows/cross-platform-test.yml

@@ -116,7 +116,7 @@ jobs:
 
     - name: Install dependencies with Poetry
       run: |
-        poetry install --no-dev
+        poetry install --only=main
 
     - name: Verify environment markers worked correctly
       run: |