switch from nightly to 0.7 on CI

[mlubin]

nightly has already switch to 1.0-DEV

[codecov]

Codecov Report

Merging #1398 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1398   +/-   ##
=======================================
  Coverage   89.78%   89.78%           
=======================================
  Files          25       25           
  Lines        3544     3544           
=======================================
  Hits         3182     3182           
  Misses        362      362

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