Fix broken tests and eliminate depwarns

[timholy]

The deprecation warnings (which are not shown unless you run with Pkg.test) made the package dreadfully slow, so these needed fixing.

CC @ashwani-rathee

[codecov]

Codecov Report

Patch coverage: 100.00% and project coverage change: +0.03 🎉

Comparison is base (1bc7795) 98.37% compared to head (1bf507d) 98.40%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #104      +/-   ##
==========================================
+ Coverage   98.37%   98.40%   +0.03%     
==========================================
  Files          11       11              
  Lines         799      817      +18     
==========================================
+ Hits          786      804      +18     
  Misses         13       13              

Impacted Files	Coverage Δ
src/ImageFeatures.jl	100.00% <ø> (ø)
src/brisk.jl	100.00% <100.00%> (ø)
src/core.jl	100.00% <100.00%> (ø)
src/corner.jl	100.00% <100.00%> (ø)
src/freak.jl	98.73% <100.00%> (ø)
src/glcm.jl	100.00% <100.00%> (ø)
src/lbp.jl	100.00% <100.00%> (ø)

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