fix syntax of altermanager::receivers #548

Job	Run time
Setup Test Matrix	22s
Puppet 8 (Ruby 3.2)	29s
Puppet 7 (Ruby 2.7)	14s
Puppet 8 - OracleLinux 8	13s
Puppet 7 - OracleLinux 8	15s
Puppet 8 - OracleLinux 9	14s
Puppet 7 - OracleLinux 9	16s
Puppet 8 - CentOS 7	16s
Puppet 7 - CentOS 7	17s
Puppet 8 - CentOS 8	11s
Puppet 7 - CentOS 8	21s
Puppet 8 - CentOS 9	12s
Puppet 7 - CentOS 9	15s
Puppet 8 - AlmaLinux 8	12s
Puppet 7 - AlmaLinux 8	17s
Puppet 8 - AlmaLinux 9	14s
Puppet 7 - AlmaLinux 9	16s
Puppet 8 - Rocky 8	12s
Puppet 7 - Rocky 8	15s
Puppet 8 - Rocky 9	15s
Puppet 7 - Rocky 9	14s
Puppet 8 - Debian 10	13s
Puppet 7 - Debian 10	17s
Puppet 8 - Debian 11	14s
Puppet 7 - Debian 11	14s
Puppet 8 - Debian 12	13s
Puppet 7 - Debian 12	15s
Puppet 8 - Ubuntu 20.04	14s
Puppet 7 - Ubuntu 20.04	14s
Puppet 8 - Ubuntu 22.04	13s
Puppet 7 - Ubuntu 22.04	15s
Distro Puppet - Archlinux rolling	14s
Test suite	1s
	8m 7s

Provide feedback