Fix equality for infinities of different types

[omus]

Fixes: #29

[codecov]

Codecov Report

Merging #30 into master will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##            master       #30   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           20        20           
  Lines          190       192    +2     
=========================================
+ Hits           190       192    +2     

Impacted Files	Coverage Δ
src/infinite/comparison.jl	100.00% <100.00%> (ø)

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