search: handle name@v.v formulae.

Before this change:
```
~> brew search openssl@1.1
openssl@1.1 ✔
==> Did you mean to perform a regular expression search?
==> Surround your query with /slashes/ to search by regex.
```

Library/Homebrew/cmd/search.rb

@@ -83,7 +83,7 @@ module Homebrew
     end
 
     if $stdout.tty?
-      metacharacters = %w[\\ | ( ) [ ] { } ^ $ * + ? .]
+      metacharacters = %w[\\ | ( ) [ ] { } ^ $ * + ?]
       bad_regex = metacharacters.any? do |char|
         ARGV.any? do |arg|
           arg.include?(char) && !arg.start_with?("/")