Updated upgrade script that is informing user that Gitea service has to be running in order to upgrade it (#24260)

Hello sir,
This pull request solves issue #23949
I have updated the upgrade script such that it will check if the Gitea
service is running, if it's not running then it will exit the process
and if it's running then the process will move further ahead.
Thank You.

---------

Co-authored-by: Giteabot <teabot@gitea.io>
Co-authored-by: silverwind <me@silverwind.io>

contrib/upgrade.sh

@@ -10,6 +10,15 @@
 #   upgrade.sh 1.15.10
 #   giteahome=/opt/gitea giteaconf=$giteahome/app.ini upgrade.sh
 
+# Check if gitea service is running
+if ! pidof gitea &> /dev/null; then
+  echo "Error: gitea is not running."
+  exit 1
+fi
+
+# Continue with rest of the script if gitea is running
+echo "Gitea is running. Continuing with rest of script..."
+
 # apply variables from environment
 : "${giteabin:="/usr/local/bin/gitea"}"
 : "${giteahome:="/var/lib/gitea"}"