Remove -h for preferred hash configuration

This option was in conflict with the help display.

cmd/csaf_downloader/config.go

@@ -88,7 +88,7 @@ type config struct {
 	ignorePattern filter.PatternMatcher
 
 	//lint:ignore SA5008 We are using choice or than once: sha256, sha512
-	PreferredHash hashAlgorithm `long:"preferred_hash" short:"h" choice:"sha256" choice:"sha512" value-name:"HASH" description:"HASH to prefer" toml:"preferred_hash"`
+	PreferredHash hashAlgorithm `long:"preferred_hash" choice:"sha256" choice:"sha512" value-name:"HASH" description:"HASH to prefer" toml:"preferred_hash"`
 }
 
 // configPaths are the potential file locations of the config file.