Fixes FileIO 1.6 deprecation

[johnnychen94]

See https://github.com/JuliaIO/FileIO.jl/pull/309/files for the compat note.

This fixes the test failures in master.

[codecov]

Codecov Report

Merging #31 (b68b1bc) into master (9cd9440) will decrease coverage by 1.06%.
The diff coverage is 75.00%.

@@            Coverage Diff             @@
##           master      #31      +/-   ##
==========================================
- Coverage   90.54%   89.47%   -1.07%     
==========================================
  Files           2        3       +1     
  Lines          74       76       +2     
==========================================
+ Hits           67       68       +1     
- Misses          7        8       +1     

Impacted Files	Coverage Δ
src/ImageShow.jl	40.00% <ø> (ø)
src/compat.jl	50.00% <50.00%> (ø)
src/showmime.jl	94.20% <100.00%> (ø)

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[timholy]

Thanks for doing this! What were the test failures? A depwarn shouldn't trigger a failure, so this concerning.

[johnnychen94]

The warning message in

ImageShow.jl/test/writemime.jl

Line 123 in 48ababc

@test_logs (:info, r"^For better quality") show(file, MIME("image/png"), Gray.(A), minpixels=0, maxpixels=5)

was polluted by the FileIO depwarn. No functionality breakage.

[timholy]

Whew! I've had enough of those, I was worried I needed one more!