ci: rename bump secret to BUMP_TOKEN

Gitea reserves the GITEA_ prefix for secret names, so the workflow secret
can't be GITEA_TOKEN. Rename it (and the env var the script reads) to
BUMP_TOKEN.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.gitea/workflows/bump.yaml

@@ -26,9 +26,9 @@ jobs:
 
       - name: Check for new release and open PR
         env:
-          GITEA_TOKEN: ${{ secrets.GITEA_TOKEN }}
+          BUMP_TOKEN: ${{ secrets.BUMP_TOKEN }}
         run: |
           host=${GITHUB_SERVER_URL#http://}; host=${host#https://}
-          curl -fsSL "http://x-access-token:${GITEA_TOKEN}@${host}/${GITHUB_REPOSITORY}/raw/branch/master/scripts/bump-version.sh" \
+          curl -fsSL "http://x-access-token:${BUMP_TOKEN}@${host}/${GITHUB_REPOSITORY}/raw/branch/master/scripts/bump-version.sh" \
             -o /tmp/bump-version.sh
           bash /tmp/bump-version.sh