Switch to using invokelatest

[omus]

Updates the code to make use of the invokelatestadded in JuliaLang/julia#19784

[omus]

If for some reason people don't like that this package now depends on Compat I can always use:

if isdefined(Base, :invokelatest)
    invokelatest = Base.invokelatest
else
    function invokelatest(f::Function, args...)
        # Note that we need to QuoteNode args to handle Symbols in args.
        eval(Expr(:call, f, map(QuoteNode, args)...))
    end
end

[rofinn]

IMHO, Compat seems like a pretty minimal dependency given that Mocking is supporting 4 different julia versions.

[codecov]

Codecov Report

Merging #20 into master will not change coverage.
The diff coverage is 100%.

@@          Coverage Diff           @@
##           master     #20   +/-   ##
======================================
  Coverage    93.2%   93.2%           
======================================
  Files           2       2           
  Lines         162     162           
======================================
  Hits          151     151           
  Misses         11      11

Impacted Files	Coverage Δ
src/Mocking.jl	87.5% <100%> (ø)	⬆️

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