chore: pin at development branch version of tool

Author: samrose

.github/workflows/test.yml

@@ -156,7 +156,7 @@ jobs:
 
       - name: verify schema.sql is committed
         run: |
-          sudo nix run .#dbmate-tool -- --version ${{ env.PGMAJOR }}
+          sudo nix run github:supabase/postgres#dbmate-tool -- --version ${{ env.PGMAJOR }}
           if ! git diff --exit-code --quiet migrations/schema-${{ env.PGMAJOR }}.sql; then
             echo "Detected changes in schema.sql:"
             git diff migrations/schema-${{ env.PGMAJOR }}.sql