Release version 5.0.3 with security updates and bug fixes (#1995)

- Updated golang.org/x/net from v0.35.0 to v0.37.0 for security
improvements.
- Built the plugin with Go version 1.24.1.
- Fixed basic authentication issues for Zabbix versions <7.2.
- Bumped grafana-plugin-sdk-go from v0.270.0 to v0.274.0.

package.json

@@ -1,6 +1,6 @@
 {
   "name": "grafana-zabbix",
-  "version": "5.0.2",
+  "version": "5.0.3",
   "description": "Zabbix plugin for Grafana",
   "homepage": "http://grafana-zabbix.org",
   "bugs": {