use v1 instead of v1.5 in CI

[jishnub]

v1 will automatically expand to the latest released version, so we won't need to update ci.yml at every minor release.

[codecov-io]

Codecov Report

Merging #42 (bdaa666) into master (a714e9d) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #42   +/-   ##
=======================================
  Coverage   85.27%   85.27%           
=======================================
  Files           1        1           
  Lines         163      163           
=======================================
  Hits          139      139           
  Misses         24       24           

---

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 a714e9d...bdaa666. Read the comment docs.