Bump version to 0.8.0dev

[ethanwharris]

What does this PR do?

Fixes # (issue)

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[codecov]

Codecov Report

Merging #1176 (5a10d8a) into master (b28a4e9) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #1176   +/-   ##
=======================================
  Coverage   90.93%   90.93%           
=======================================
  Files         283      283           
  Lines       12699    12699           
=======================================
  Hits        11548    11548           
  Misses       1151     1151           

Flag	Coverage Δ
unittests	90.93% <100.00%> (ø)

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

Impacted Files	Coverage Δ
flash/__about__.py	100.00% <100.00%> (ø)

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