S3UploadThread fix bug with regex search on bytes

[OscarLuu]

Fixes a bug where S3UploadThread tries to do regex on a bytes object.

[E 240708 22:31:58 S3UploadThread:46] Error uploading barfoo: cannot use a string pattern on a bytes-like object
[E 240708 22:31:59 S3UploadThread:46] Error uploading foobar: cannot use a string pattern on a bytes-like object
Exception: [((<class 'TypeError'>, TypeError('cannot use a string pattern on a bytes-like object'), <traceback object at 0x7f9ec8846d80>), <S3UploadThread(Thread-9, started daemon 140319659054848)>), ((<class 'TypeError'>, TypeError('cannot use a string pattern on a bytes-like object'), <traceback object at 0x7f9eb41d60c0>), <S3UploadThread(Thread-9, started daemon 140319659054848)>)]