chore: applied shellcheck suggestions on get_latest_release.sh

Signed-off-by: Florent Poinsard <florent.poinsard@outlook.fr>

tools/get_latest_release.sh

@@ -25,9 +25,9 @@ target_release=""
 base_release_branch=$(echo "$1" | grep -E 'release-[0-9]*.0$')
 if [ "$base_release_branch" != "" ]; then
   major_release=$(echo "$base_release_branch" | sed 's/release-*//' | sed 's/\.0//')
-  target_release="release-$((${major_release}-1)).0"
+  target_release="release-$((major_release-1)).0"
 else
   target_release="release-$(git show-ref | grep -E 'refs/remotes/origin/release-[0-9]*\.0$' | sed 's/[a-z0-9]* refs\/remotes\/origin\/release-//' | sort -nr | head -n1)"
 fi
 
-echo $target_release
+echo "$target_release"