Change package_name because it's not debian compatible

Author: aleroyer

.goreleaser.yml

@@ -29,7 +29,8 @@ archives:
       linux: Linux
       amd64: x86_64
 nfpms:
-  - homepage: https://github.com/aleroyer/rsyslog_exporter
+  - package_name: "rsyslog-exporter"
+    homepage: https://github.com/aleroyer/rsyslog_exporter
     description: rsyslog-exporter for prometheus
     maintainer: Antoine Leroyer <[email protected]>
     license: Apache 2.0