Refactor Marshal function in filter encoder

- Simplified the key-value appending logic in the Marshal function by replacing manual string appending with the text.AppendQuote method for better readability and maintainability.
- Updated version number to v0.19.9 to reflect the changes made.

pkg/encoders/filter/filter.go

@@ -212,9 +212,7 @@ func (f *F) Marshal(dst []byte) (b []byte) {
 		dst = append(dst, '"', '#', tKey[0], '"', ':')
 		dst = append(dst, '[')
 		for i, value := range values {
-				dst = append(dst, '"')
-				dst = append(dst, value...)
-				dst = append(dst, '"')
+			dst = text.AppendQuote(dst, value, text.NostrEscape)
 			if i < len(values)-1 {
 				dst = append(dst, ',')
 			}

pkg/version/version

@@ -1 +1 @@
-v0.19.8
+v0.19.9