Update isAbsoluteURL.js (axios#3809)

Escaping non-special characters in strings, template literals, and regular expressions doesn't have any effect, as demonstrated in the following example:

https://eslint.org/docs/rules/no-useless-escape

Co-authored-by: Jay <jasonsaayman@gmail.com>

lib/helpers/isAbsoluteURL.js

@@ -10,5 +10,5 @@ module.exports = function isAbsoluteURL(url) {
   // A URL is considered absolute if it begins with "<scheme>://" or "//" (protocol-relative URL).
   // RFC 3986 defines scheme name as a sequence of characters beginning with a letter and followed
   // by any combination of letters, digits, plus, period, or hyphen.
-  return /^([a-z][a-z\d\+\-\.]*:)?\/\//i.test(url);
+  return /^([a-z][a-z\d+\-.]*:)?\/\//i.test(url);
 };