Allow underscore and tilde in URI hostnames as per RFC 3986 (#853)

The implementation of [RFC
3986](https://datatracker.ietf.org/doc/html/rfc3986) in the URI
validator is more strict than the specification allows. While the RFC
says

> URI producers should use names that conform to the DNS syntax, even
when use of DNS is not immediately apparent

the host component grammar actually allows more characters than are
allowed in DNS names.

This is a problem for the Drupal project which uses this package in
conjunction with custom stream wrappers with module names in the host
component. Module names conform to PHP function name standards, not DNS
standards - that is, they allow underscores but not dashes.

The relevant RFC grammar is
```
      host        = IP-literal / IPv4address / reg-name

      reg-name    = *( unreserved / pct-encoded / sub-delims )

      unreserved  = ALPHA / DIGIT / "-" / "." / "_" / "~"
```

This PR widens the `host` validation to allow all characters in the
`unreserved` set. While `pct-encoded` and `sub-delims` are also
technically allowed, this is the smallest change that will help us out.

---------

Co-authored-by: Danny van der Sluijs <danny.vandersluijs@icloud.com>

Author: longwave

CHANGELOG.md

@@ -6,6 +6,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
+### Fixed
+- Allow underscore and tilde in URI hostnames as per RFC 3986 ([#853](https://github.com/jsonrainbow/json-schema/pull/853))
 
 ## [6.6.1] - 2025-11-07
 ### Changed

src/JsonSchema/Tool/Validator/UriValidator.php

@@ -12,7 +12,7 @@ public static function isValid(string $uri): bool
         $hierarchicalPattern = '/^
             ([a-z][a-z0-9+\-.]*):\/\/                # Scheme (http, https, ftp, etc.)
             (?:([^:@\/?#]+)(?::([^@\/?#]*))?@)?      # Optional userinfo (user:pass@)
-            ([a-z0-9.-]+|\[[a-f0-9:.]+\])            # Hostname or IPv6 in brackets
+            ([a-z0-9._~-]+|\[[a-f0-9:.]+\])          # Hostname or IPv6 in brackets
             (?::(\d{1,5}))?                          # Optional port
             (\/[a-zA-Z0-9._~!$&\'()*+,;=:@\/%-]*)*   # Path (valid characters only)
             (\?([^#]*))?                             # Optional query

tests/Tool/Validator/UriValidatorTest.php

@@ -32,6 +32,8 @@ public function validUriDataProvider(): \Generator
         yield 'Data URI' => ['uri' => 'data:text/plain;charset=utf-8,Hello%20World!'];
         yield 'ISBN URN URI' => ['uri' => 'urn:isbn:0451450523'];
         yield 'OASIS URN URI' => ['uri' => 'urn:oasis:names:specification:docbook:dtd:xml:4.1.2'];
+        yield 'Custom URI with underscore' => ['uri' => 'custom://reg_name/path/file.json'];
+        yield 'Custom URI with tilde' => ['uri' => 'custom://reg~name/path/file.json'];
     }
 
     public function invalidUriDataProvider(): \Generator