chore(CI): fix relup tests error

.github/workflows/run_fvt_tests.yaml

@@ -213,9 +213,9 @@ jobs:
 
             pre_vsn="$(echo $vsn | grep -oE '^[0-9]+.[0-9]')"
             if  [ $PROFILE = "emqx" ]; then
-                old_vsns="$(git tag -l "v$pre_vsn.[0-9]" | tr "\n" " " | sed "s/v$vsn//")"
+                old_vsns="$(git tag -l "v$pre_vsn.[0-9]" | xargs echo -n | sed "s/v$vsn//")"
             else
-                old_vsns="$(git tag -l "e$pre_vsn.[0-9]" | tr "\n" " " | sed "s/v$vsn//")"
+                old_vsns="$(git tag -l "e$pre_vsn.[0-9]" | xargs echo -n | sed "s/v$vsn//")"
             fi
             echo "OLD_VSNS=$old_vsns" >> $GITHUB_ENV
         - name: download emqx
@@ -241,7 +241,7 @@ jobs:
         - name: run relup test
           run: |
             set -e -x -u
-            if [ -n "$OLD_VSNS" ]; then
+            if [ -n "{$OLD_VSNS// }" ]; then
                 mkdir -p packages
                 cp emqx/_packages/emqx/*.zip packages
                 cp emqx/*.zip packages