unix-ffi/json: Fix #985 by accepting both str and bytes as arg for json.loads()

Same as micropython's internal json lib does.

Signed-off-by: Dominik Heidler <dheidler@suse.de>

Author: aylen384

unix-ffi/json/json/__init__.py

@@ -413,4 +413,6 @@ def loads(
         kw["parse_int"] = parse_int
     if parse_constant is not None:
         kw["parse_constant"] = parse_constant
+    if isinstance(s, bytes):
+        s = s.decode('utf-8')
     return cls(**kw).decode(s)