fix: remove mailto,tel,sms from the default valid schemas

It seems there are few use cases.

Author: kenjis

system/Validation/FormatRules.php

@@ -308,7 +308,7 @@ public function valid_url_strict(?string $str = null, ?string $validSchemes = nu
         $scheme       = strtolower(parse_url($str, PHP_URL_SCHEME));
         $validSchemes = explode(
             ',',
-            strtolower($validSchemes ?? 'http,https,mailto,tel,sms')
+            strtolower($validSchemes ?? 'http,https')
         );
 
         return in_array($scheme, $validSchemes, true)

tests/system/Validation/FormatRulesTest.php

@@ -214,7 +214,7 @@ public function urlProvider()
             [
                 'mailto:support@codeigniter.com',
                 true,
-                true,
+                false,
             ],
             [
                 '//example.com',

user_guide_src/source/libraries/validation.rst

@@ -863,12 +863,11 @@ valid_ip                No         Fails if the supplied IP is not valid.
 valid_url               No         Fails if field does not contain (loosely) a
                                    URL. Includes simple strings that could be
                                    hostnames, like "codeigniter".
-valid_url_strict        Yes        Fails if field does not contain a valid URL.  valid_url_strict[http,https]
+valid_url_strict        Yes        Fails if field does not contain a valid URL.  valid_url_strict[https]
                                    Roughly equivalent to a "fail anything that
                                    would not be a clickable link." You can
                                    optionally specify a list of valid schemas.
-                                   If not specified,
-                                   ``http,https,mailto,tel,sms`` are valid.
+                                   If not specified, ``http,https`` are valid.
 valid_date              No         Fails if field does not contain a valid date. valid_date[d/m/Y]
                                    Accepts an optional parameter to matches
                                    a date format.