NR-428155: fix code coverage inclusion in release mode · newrelic/newrelic-ios-agent@f0a8e6e

Failed to load cask: ./lcov.rb Cask 'lcov' is unreadable: wrong constant name #<Class:0x000000013aad1368>

lcov 2.3.1 is available and more recent than version 1.16.

Treating ./lcov.rb as a formula.