Raku: Fix incorrectly matching closing brackets as opening

lexers/r/raku.go

@@ -1156,12 +1156,11 @@ func rakuRules() Rules {
 	}
 }
 
-// Joins keys and values of rune map
+// Joins keys of rune map
 func joinRuneMap(m map[rune]rune) string {
-	runes := make([]rune, 0, len(m)*2)
-	for k, v := range m {
+	runes := make([]rune, 0, len(m))
+	for k := range m {
 		runes = append(runes, k)
-		runes = append(runes, v)
 	}
 
 	return string(runes)

lexers/testdata/raku.actual

@@ -21,7 +21,7 @@ fmt.Println("Hello from Go")
 say $=pod[0].config<numbered>;
 
 sub f1($a) {
-    $a+1;
+    $a+1; #=> Comment looking like a pod declaration, but with a closing bracket!
 }
 
 2.&f1;

lexers/testdata/raku.expected

@@ -67,6 +67,8 @@
   {"type":"Operator","value":"+"},
   {"type":"LiteralNumberInteger","value":"1"},
   {"type":"Punctuation","value":";"},
+  {"type":"Text","value":" "},
+  {"type":"CommentSingle","value":"#=\u003e Comment looking like a pod declaration, but with a closing bracket!"},
   {"type":"Text","value":"\n"},
   {"type":"Punctuation","value":"}"},
   {"type":"Text","value":"\n\n"},