fixes encoding error

[tanish14]

fixes #3204

Added encoding='utf8' to the arguments of open() which no longer shows an error and works fine

[shaka-bot]

Test Failure:

Traceback (most recent call last):
TypeError: 'encoding' is an invalid keyword argument for this function
Build step 'Execute shell' marked build as failure

[joeyparrish]

Looks like you'll need to make sure it works in both python2 and python3. Thanks!

[surajkumar-sk]

Hi , I am participating in GSOC 2021 . I would love to work on Shaka player for this gsoc . I am trying to understand this project .
When i try to compile the library i get this issue #3204 . tanish14 has given a perfect solution which works for python 3 but fails on python 2. for dealing with encoding files in python2, io.open() should be used . open() works perfectly in python3 for dealing with encoding files but not in python2 . i would like to PR the changes combining @tanish14 and my changes .