utils/curl.rb: accept 1xx HTTP status codes

RFC 2616 states:

A client MUST be prepared to accept one or more 1xx status responses
prior to a regular response, even if the client does not expect a 100
(Continue) status message. Unexpected 1xx status responses MAY be
ignored by a user agent.

In the rare cases that we encounter a formula URL with a server that
provides a preliminary 1xx status code, it seems that (at least during
audit) we are failing on encountering this status code, even though
retrieving the file will succeed without issues.

Library/Homebrew/utils/curl.rb

@@ -94,7 +94,7 @@ def curl_check_http_content(url, user_agents: [:default], check_content: false,
   user_agents.each do |ua|
     details = curl_http_content_headers_and_checksum(url, hash_needed: hash_needed, user_agent: ua)
     user_agent = ua
-    break if details[:status].to_s.start_with?("2")
+    break if (100..299).include?(details[:status].to_i)
   end
 
   unless details[:status]
@@ -104,7 +104,7 @@ def curl_check_http_content(url, user_agents: [:default], check_content: false,
     return "The URL #{url} is not reachable"
   end
 
-  unless details[:status].start_with? "2"
+  unless (100..299).include?(details[:status].to_i)
     return "The URL #{url} is not reachable (HTTP status code #{details[:status]})"
   end
 
@@ -119,8 +119,8 @@ def curl_check_http_content(url, user_agents: [:default], check_content: false,
   secure_details =
     curl_http_content_headers_and_checksum(secure_url, hash_needed: true, user_agent: user_agent)
 
-  if !details[:status].to_s.start_with?("2") ||
-     !secure_details[:status].to_s.start_with?("2")
+  if !(100..299).include?(details[:status].to_i) ||
+     !(100..299).include?(secure_details[:status].to_i)
     return
   end