fix: badly anchored regexes (#3181)

Regex should now cover multiline strings

Fixes https://github.com/faker-ruby/faker/security/code-scanning/4
Fixes https://github.com/faker-ruby/faker/security/code-scanning/3
Fixes https://github.com/faker-ruby/faker/security/code-scanning/2

Author: thdaraujo

lib/faker/default/avatar.rb

@@ -37,7 +37,7 @@ class << self
       #
       # @faker.version 1.4.3
       def image(slug: nil, size: '300x300', format: 'png', set: 'set1', bgset: nil)
-        raise ArgumentError, 'Size should be specified in format 300x300' unless size =~ /^[0-9]+x[0-9]+$/
+        raise ArgumentError, 'Size should be specified in format 300x300' unless size =~ /\A[0-9]+x[0-9]+\z/
         raise ArgumentError, "Supported formats are #{SUPPORTED_FORMATS.join(', ')}" unless SUPPORTED_FORMATS.include?(format)
 
         slug ||= Faker::Lorem.words.join

lib/faker/default/lorem_flickr.rb

@@ -96,7 +96,7 @@ def colorized_image(size: '300x300', color: 'red', search_terms: ['all'], match_
       private
 
       def build_url(size, format, search_terms, match_all)
-        raise ArgumentError, 'Size should be specified in format 300x300' unless size =~ /^[0-9]+x[0-9]+$/
+        raise ArgumentError, 'Size should be specified in format 300x300' unless size =~ /\A[0-9]+x[0-9]+\z/
 
         url_parts = ['https://loremflickr.com']
         url_parts << format

lib/faker/default/placeholdit.rb

@@ -30,7 +30,7 @@ def image(size: '300x300', format: 'png', background_color: nil, text_color: nil
         background_color = generate_color if background_color == :random
         text_color = generate_color if text_color == :random
 
-        raise ArgumentError, 'Size should be specified in format 300x300' unless size =~ /^[0-9]+x[0-9]+$/
+        raise ArgumentError, 'Size should be specified in format 300x300' unless size =~ /\A[0-9]+x[0-9]+\z$/
         raise ArgumentError, "Supported formats are #{SUPPORTED_FORMATS.join(', ')}" unless SUPPORTED_FORMATS.include?(format)
         raise ArgumentError, "background_color must be a hex value without '#'" unless background_color.nil? || background_color =~ /((?:^\h{3}$)|(?:^\h{6}$)){1}(?!.*\H)/
         raise ArgumentError, "text_color must be a hex value without '#'" unless text_color.nil? || text_color =~ /((?:^\h{3}$)|(?:^\h{6}$)){1}(?!.*\H)/