运行gem install prdns，遇错

[briteming]

hi.
在mac上。
yudeMacBook-Air:~ brite$ gem install prdns
ERROR: Loading command: install (LoadError)
dlopen(/usr/local/Cellar/ruby/2.6.3/lib/ruby/2.6.0/x86_64-darwin16/openssl.bundle, 9): Library not loaded: /usr/local/opt/openssl/lib/libssl.1.0.0.dylib
Referenced from: /usr/local/Cellar/ruby/2.6.3/lib/ruby/2.6.0/x86_64-darwin16/openssl.bundle
Reason: image not found - /usr/local/Cellar/ruby/2.6.3/lib/ruby/2.6.0/x86_64-darwin16/openssl.bundle
ERROR: While executing gem ... (NoMethodError)
undefined method `invoke_with_build_args' for nil:NilClass
yudeMacBook-Air:~ brite$ which gem
/usr/local/opt/ruby/bin/gem
yudeMacBook-Air:~ brite$ which ruby
/usr/local/opt/ruby/bin/ruby
yudeMacBook-Air:~ brite$ gem --version
3.0.3
yudeMacBook-Air:~ brite$

怎么解决？