Add julia version upper bound for CI

[yuehhua]

No description provided.

[codecov-commenter]

Codecov Report

Merging #27 (b240782) into master (ad6b55e) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##            master       #27   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            2         2           
  Lines           50        52    +2     
=========================================
+ Hits            50        52    +2     

Impacted Files	Coverage Δ
src/fourier.jl	100.00% <0.00%> (ø)

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[foldfelis]

@yuehhua please add CI for Windows for me will you. Sorry I'm so busy lately...

[foldfelis]

BTW, just checking, did you find the solution to the type unstable problem here ?

[yuehhua]

@yuehhua please add CI for Windows for me will you. Sorry I'm so busy lately...

Done.

BTW, just checking, did you find the solution to the type unstable problem here ?

Not yet, I am currently working on implementing wavelet transform and its operators.

[foldfelis]

Not yet, I am currently working on implementing wavelet transform and its operators.

any Ref ?

[yuehhua]

You can check #29.