typeerror: a bytes-like object is required, not ‘str’ Solution

You opened the file in binary mode:

with open(fname, 'rb') as f:
This means that all data read from the file is returned as bytes objects, not str. You cannot then use a string in a containment test:

if 'some-pattern' in tmp: continue
You'd have to use a bytes object to test against tmp instead:

if b'some-pattern' in tmp: continue
or open the file as a textfile instead by replacing the 'rb' mode with 'r'.