fix(ci): hardcode REF to main to isolate gitea output bug

.gitea/workflows/deploy.yml

@@ -82,10 +82,7 @@ jobs:
         id: determine
         shell: bash
         run: |
-          REF="$GITHUB_REF_NAME"
-          if [ -z "$REF" ]; then
-            REF=$(git rev-parse --abbrev-ref HEAD | sed 's/HEAD//')
-          fi
+          REF="main"
           SHORT_SHA=$(echo "${{ github.sha }}" | cut -c1-7)
           DOMAIN="e-tib.com"
           PRJ="etib"