Fix PhoneticTokenFilter (#2589) (#2590)

(cherry picked from commit 5fa8ede)

Co-authored-by: Florian Bernd <[email protected]>

Author: github-actions[bot]

specification/_types/analysis/phonetic-plugin.ts

@@ -64,7 +64,7 @@ export enum PhoneticRuleType {
 export class PhoneticTokenFilter extends TokenFilterBase {
   type: 'phonetic'
   encoder: PhoneticEncoder
-  languageset: PhoneticLanguage[]
+  languageset: PhoneticLanguage | PhoneticLanguage[]
   max_code_len?: integer
   name_type: PhoneticNameType
   replace?: boolean