build(chart): fix version detection

.github/workflows/main.yml

@@ -101,7 +101,7 @@ jobs:
           # Release new chart only if its version changes
           helm repo add otomi https://otomi.io/otomi-core
           helm repo update
-          this_version=v$(cat chart/otomi/Chart.yaml | yq r - 'version')
+          this_version=$(cat chart/otomi/Chart.yaml | yq r - 'version')
           chart_version=$(helm search repo otomi -o json | jq -r 'sort_by(.version) | .[-1].version')
           [ "$this_version" = "$chart_version" ] && echo "The current version ($this_version) is the same as the last released version ($chart_version). Skipping chart release." && exit
           echo ::set-output name=has_changes::true