Update trigger-book-build.yaml to use ProjecPythia action instead of brian's personal (#527)

* Update trigger-book-build.yaml

* Update .github/workflows/trigger-book-build.yaml

---------

Co-authored-by: Brian Rose <brose@albany.edu>

Author: jukent

.github/workflows/trigger-book-build.yaml

@@ -4,7 +4,7 @@ on:
 
 jobs:
   build:
-    uses: brian-rose/cookbook-actions/.github/workflows/build-book.yaml@myst-defaults
+    uses: ProjectPythia/cookbook-actions/.github/workflows/build-book.yaml@main
     with:
       artifact_name: book-zip-${{ github.event.number }}
       base_url: '/_preview/${{ github.event.number }}'