fix: promu version

Author: christiangda

.promu.yml

@@ -1,7 +1,7 @@
 go:
   # Whenever the Go version is updated here, .circle/config.yml should also
   # be updated.
-  version: 1.14
+  version: 1.18
 
 repository:
   path: github.com/slashdevops/aws_cloudwatch_exporter