charm-tools: Depends on gmp for Linuxbrew (#2865)
charm-tools: Depends on gmp for Linuxbrew (#2865)

Resource pycrypto depends on gmp.
Fix the error:
Unwanted system libraries:
  libgmp.so.10
maxim-belkin/homebrew-core,Linuxbrew/homebrew-core,rwhogg/homebrew-core,Linuxbrew/homebrew-core,LinuxbrewTestBot/homebrew-core,maxim-belkin/homebrew-core,rwhogg/homebrew-core,LinuxbrewTestBot/homebrew-core