internal/rosa/perl: check stable versions

This uses odd-even versioning.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/rosa/perl.go

@@ -56,6 +56,9 @@ func init() {
 		Website:     "https://www.perl.org/",
 
 		ID: 13599,
+
+		// odd-even versioning
+		latest: (*Versions).getStable,
 	}
 }