make jwtf_keystore compatible with erlang 19
diff --git a/src/jwtf/src/jwtf_keystore.erl b/src/jwtf/src/jwtf_keystore.erl
index be261e6..3f7d2dc 100644
--- a/src/jwtf/src/jwtf_keystore.erl
+++ b/src/jwtf/src/jwtf_keystore.erl
@@ -140,7 +140,7 @@
     end.
 
 pem_decode(PEM) ->
-    BinPEM = iolist_to_binary(string:replace(PEM, "\\n", "\n", all)),
+    BinPEM = iolist_to_binary(lists:join("\n", string:split(PEM, "\\n", all))),
     case public_key:pem_decode(BinPEM) of
         [PEMEntry] ->
             public_key:pem_entry_decode(PEMEntry);