ci: use tag name instead of GIT_REF

The stable release publish was
triggered by the release: published event,
which intermittently delivers an empty
github.ref (actions/runner#2788).
using github.event.release.tag_name instead,
as this is the preferred method for
referencing the tag name of a release.

Signed-off-by: Madhu Rajanna <madhupr007@gmail.com>
(cherry picked from commit f21d71c)

Author: Madhu-1

.github/workflows/publish-helm-charts.yaml

@@ -22,7 +22,9 @@ jobs:
 
       - name: Set release version
         id: release_version
-        run: echo "VERSION=${GITHUB_REF#refs/tags/v}" >> $GITHUB_ENV
+        run: echo "VERSION=${TAG_NAME#v}" >> $GITHUB_ENV
+        env:
+          TAG_NAME: ${{ github.event.release.tag_name }}
 
 
       - name: Install helm