Bump Go to 1.25 in copilot-setup-steps to satisfy gh-aw go.mod

Agent-Logs-Url: https://github.com/githubnext/tsessebe/sessions/dacd4ac4-ace5-4ec5-b2f9-60cbcabca784

Co-authored-by: mrjf <180956+mrjf@users.noreply.github.com>

Author: Copilot

.github/workflows/copilot-setup-steps.yml

@@ -29,7 +29,7 @@ jobs:
       - name: Set up Go
         uses: actions/setup-go@v6
         with:
-          go-version: '1.24'
+          go-version: '1.25'
       - name: Build and install gh-aw from main (pinned commit)
         env:
           GH_AW_REF: a91e3d2deadaf27496e563b7a4591125e1093d22