Explicit cast from dict to str to avoid TypeError (#11)

- Explicit cast from dict to str to avoid TypeError (aa17014f6f3c345803b08f64d026ed7c78e58dfc)

the_pile.py

@@ -248,7 +248,7 @@ class ThePile(datasets.GeneratorBasedBuilder):
                         text = file.read().decode("utf-8", errors="ignore")  # encoding errors in enron_emails
                         yield key, {
                             "text": text,
-                            "meta": meta,
+                            "meta": str(meta),
                         }
                         key += 1
                 elif subset in {"uspto", "github"}: