Remove stray backslashes from check_ssl_cert
Fix stray backslash before empty spaces. Replace them with empty spaces or \s
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Those stray backslashes make autopkgtest to fail by the warnings produced by grep 3.8-2. See: https://ci.debian.net/data/autopkgtest/unstable/amd64/n/nagios-plugins-contrib/26117196/log.gz grep upstream states the warning will become errors in the future.