Update KrylovKit compat bound, extend CI to recent Julia versions

[pablosanjose]

Let's see if Julia 1.3-rc1 and nightly pass tests

[codecov-commenter]

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Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.40%. Comparing base (c149d20) to head (a09ba01).
⚠️ Report is 1 commits behind head on master.
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Additional details and impacted files

@@            Coverage Diff             @@
##           master     #405      +/-   ##
==========================================
+ Coverage   92.31%   92.40%   +0.09%     
==========================================
  Files          41       41              
  Lines        7441     7442       +1     
==========================================
+ Hits         6869     6877       +8     
+ Misses        572      565       -7     

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