fix(stemming): use double quotes for newline characters

- replace single-quoted `\n` with double-quoted `"\n"` in `jsonl` string processing
- fix inconsistent line splitting behavior in `upsert` method

Author: tharropoulos

lib/typesense/stemming_dictionaries.rb

@@ -11,7 +11,7 @@ def initialize(api_call)
 
     def upsert(dict_id, words_and_roots_combinations)
       words_and_roots_combinations_in_jsonl = if words_and_roots_combinations.is_a?(Array)
-                                                words_and_roots_combinations.map { |combo| Oj.dump(combo, mode: :compat) }.join('\n')
+                                                words_and_roots_combinations.map { |combo| Oj.dump(combo, mode: :compat) }.join("\n")
                                               else
                                                 words_and_roots_combinations
                                               end
@@ -25,7 +25,7 @@ def upsert(dict_id, words_and_roots_combinations)
       )
 
       if words_and_roots_combinations.is_a?(Array)
-        result_in_jsonl.split('\n').map { |r| Oj.load(r) }
+        result_in_jsonl.split("\n").map { |r| Oj.load(r) }
       else
         result_in_jsonl
       end