Use PyAutoFit main_build branch in CI

The plot refactor with corner_cornerpy is on main_build, not main.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: 2 people

.github/workflows/main.yml

@@ -18,6 +18,7 @@ jobs:
       uses: actions/checkout@v2
       with:
         repository: rhayes777/PyAutoFit
+        ref: main_build
         path: PyAutoFit
     - name: Checkout PyAutoArray
       uses: actions/checkout@v2