chore: Update namespaces for uproot v4.0 and awkward v1.0

[matthewfeickert]

Update namespaces from uproot4 to uproot and awkward1 to awkward following their respective releases.

* Update namespace from uproot4 to uproot
* Update namespace from awkward1 to awkward
* Require compatible releases with uproot v4.0 and awkward v1.0

[codecov]

Codecov Report

Merging #42 (9d401ad) into master (3771527) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #42   +/-   ##
=======================================
  Coverage   28.09%   28.09%           
=======================================
  Files           7        7           
  Lines         210      210           
  Branches       39       39           
=======================================
  Hits           59       59           
  Misses        151      151           

Flag	Coverage Δ
unittests	28.09% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
src/heputils/convert.py	45.45% <ø> (ø)

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