fix initialize lr set to 0 in ResNet training

[Yancey1989]

An int variable multiple a float value would be an INT, an int value multiple a float value would be FLOAT in Go. https://play.golang.org/p/f39Vw-9p23E

[codecov[bot]]

Codecov Report

Merging #357 into develop will not change coverage. The diff coverage is n/a.

@@           Coverage Diff            @@
##           develop     #357   +/-   ##
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  Coverage    87.46%   87.46%           
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  Files           33       33           
  Lines         1468     1468           
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  Hits          1284     1284           
  Misses         121      121           
  Partials        63       63           

[shendiaomo]

An int variable multiple a float value would be an INT, an int value multiple a float value would be FLOAT in Go. https://play.golang.org/p/f39Vw-9p23E

The reason is that Go literals are untyped, see https://stackoverflow.com/questions/47213283/why-is-there-a-difference-between-floating-point-multiplication-with-literals-vs