while(<>){

  # method 1 : extract first version-like looking number
  # if string 'version' is found somehwere
   /version/i and /(\d+\.\d+(?:\.\d+)?)/ and $_ = "$1\n";

  # method 2 : extract first version-like number after
  # the string 'version'
   /version.+(\d+\.\d+(?:\.\d+)?)/i and $_ = "$1\n";

} continue { print }
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The basic idea is not to replace "everything else" but to grab what you need throw away the rest.

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