A period is a valid formula name character

Fixes Homebrew/homebrew#31052.

Library/Homebrew/tap_constants.rb

 # match expressions when taps are given as ARGS, e.g. someuser/sometap
 HOMEBREW_TAP_ARGS_REGEX = %r{^([\w-]+)/(homebrew-)?([\w-]+)$}
 # match taps' formula, e.g. someuser/sometap/someformula
-HOMEBREW_TAP_FORMULA_REGEX = %r{^([\w-]+)/([\w-]+)/([\w+-]+)$}
+HOMEBREW_TAP_FORMULA_REGEX = %r{^([\w-]+)/([\w-]+)/([\w+-.]+)$}
 # match taps' directory path, e.g. HOMEBREW_LIBRARY/Taps/someuser/sometap
 HOMEBREW_TAP_DIR_REGEX = %r{#{Regexp.escape(HOMEBREW_LIBRARY.to_s)}/Taps/([\w-]+)/([\w-]+)}
 # match taps' formula path, e.g. HOMEBREW_LIBRARY/Taps/someuser/sometap/someformula