Update parse_bytes imports to resolve deprecation warnings

[pentschev]

Resolves deprecation warnings such as the one below:

FutureWarning: parse_bytes is deprecated and will be removed in a future release. Please use dask.utils.parse_bytes instead.
    from distributed.utils import parse_bytes

[codecov-commenter]

Codecov Report

❗ No coverage uploaded for pull request base (branch-21.08@939bc26). Click here to learn what that means.
The diff coverage is n/a.

❗ Current head 2308b48 differs from pull request most recent head 6f5ea2f. Consider uploading reports for the commit 6f5ea2f to get more accurate results

@@               Coverage Diff               @@
##             branch-21.08     #662   +/-   ##
===============================================
  Coverage                ?   90.32%           
===============================================
  Files                   ?       15           
  Lines                   ?     1644           
  Branches                ?        0           
===============================================
  Hits                    ?     1485           
  Misses                  ?      159           
  Partials                ?        0           

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 939bc26...6f5ea2f. Read the comment docs.

[jacobtomlinson]

This looks good, thanks for the code hygiene here.

[jacobtomlinson]

@gpucibot merge

[pentschev]

Thanks @jacobtomlinson for review!