%TAG prefix does not accept all characters in ns-uri-char production

As noted in https://github.com/yaml/yaml-spec/issues/268#issuecomment-1208565027, Psych does not accept a %TAG prefix including a #, which seems to be due to the following code:

https://github.com/yaml/libyaml/blob/f8f760f7387d2cc56a2fc7b1be313a3bf3f7f58c/src/scanner.c#L2603-L2627

According to theYAML 1.2 Spec the ns-uri-char does include #, which is missing from the scanner.

[39] ns-uri-char ::=
    (
      '%'
      [ns-hex-digit](https://yaml.org/spec/1.2.2/#rule-ns-hex-digit){2}
    )
  | [ns-word-char](https://yaml.org/spec/1.2.2/#rule-ns-word-char)
  | '#'
  | ';'
  | '/'
  | '?'
  | ':'
  | '@'
  | '&'
  | '='
  | '+'
  | '$'
  | ','
  | '_'
  | '.'
  | '!'
  | '~'
  | '*'
  | "'"
  | '('
  | ')'
  | '['
  | ']'

This prevents creating a TAG line such as the following:

%TAG ! http://www.w3.org/2001/XMLSchema#

Start in src/scanner.c at the linked lines 2603-2627, where the %TAG prefix characters are scanned. Check the YAML 1.2 ns-uri-char production and verify that the example prefix ending in # is accepted.