1.6.4

• python_virtualenv_constants: update virtualenv to 16.0.0 (@commitay)
• Add compatibility layer for handling Cask Tap migration. (@reitermarkus)
• Move --version logic into cmd/--version.rb. (@reitermarkus)
• cask audit: installer and pkg require uninstall (@commitay)
• Remove unused include Utils. (@reitermarkus)
• Clean up compat. (@reitermarkus)
• cask upgrade: ensure cache exists (@commitay)
• better alignement (@retokromer)
• Update rubocop-cask URL. (@reitermarkus)
• Alphabetize the brew outdated formula listing. (@dougal)
• oldest_cpu: Bottling architecture of ARM is armv6 (@sjackman)
• cask caveats dsl: add license (@commitay)
• Bump rspec-retry from 0.5.7 to 0.6.0 in /Library/Homebrew/test (@Homebrew)
• Bump github-pages from 183 to 185 in /docs (@Homebrew)
• Cross-platform diagnostic (@maxim-belkin)
• reproducible-bug-report.md: update cask url (@commitay)
• add .github/issue_template.md (@commitay)
• formula: improve to_hash output. (@MikeMcQuaid)
• Move post_install from cmd to FormulaInstaller (@mrfoto)
• Remove cmd/tap requirement because it's no longer used (@mrfoto)
• Fix zap --force for uninstalled casks (@commitay)
• Use new GitHub issue template format (@MikeMcQuaid)
• vendor-install: Add portable-ruby bottle for ARM (@sjackman)
• lines_cop: Add deprected options audit for depends_on (@GauthamGoli)
• .github/ISSUE_TEMPLATE: fix newlines. (@MikeMcQuaid)
• Add more Probots (@MikeMcQuaid)
• bump-formula-pr: rename @args. (@MikeMcQuaid)