fix branch

Author: anthony-nhs

.github/workflows/sync_copilot.yml

@@ -17,6 +17,6 @@ jobs:
               uses: NHSDigital/eps-copilot-instructions@304ab2f4b7cdc15a1d7c0a0fae5290fad41b2451
               with:
                   copilot_instructions_ref: main
-                  calling_repo_base_branch: master
+                  calling_repo_base_branch: main
                   CREATE_PULL_REQUEST_APP_ID: ${{ secrets.CREATE_PULL_REQUEST_APP_ID }}
                   CREATE_PULL_REQUEST_PEM: ${{ secrets.CREATE_PULL_REQUEST_PEM }}