Add some chars (!, =, etc) as allowed to the userinfo part of authority

As per https://tools.ietf.org/html/rfc3986#section-3.2.1
userinfo    = *( unreserved / pct-encoded / sub-delims / ":" )

Where, according to https://tools.ietf.org/html/rfc3986#section-2.2 ,
sub-delims  = "!" / "$" / "&" / "'" / "(" / ")"
                  / "*" / "+" / "," / ";" / "="

The sub-delims and pct-encoded sets were added in this commit

src/rfc3986/abnf_regexp.py

@@ -132,7 +132,9 @@ HOST_RE = HOST_PATTERN = '({0}|{1}|{2})'.format(
     IPv4_RE,
     IP_LITERAL_RE,
 )
-USERINFO_RE = '^[A-Za-z0-9_.~\-%:]+'
+USERINFO_RE = '^([' + UNRESERVED_RE + SUB_DELIMITERS_RE + ':]|%s)+' % (
+    PCT_ENCODED
+)
 PORT_RE = '[0-9]{1,5}'
 
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