Make sure that email validators don't match unintentional non-ASCII local parts

library/src/actions/email/email.test.ts

@@ -299,6 +299,7 @@ describe('email', () => {
         'あいうえお@example.com',
         'email@あいうえお.com',
         'email@example.あいう',
+        'Kſ@example.com',
       ]);
     });
 

library/src/actions/rfcEmail/rfcEmail.test.ts

@@ -312,6 +312,7 @@ describe('rfcEmail', () => {
         'あいうえお@example.com',
         'email@あいうえお.com',
         'email@example.あいう',
+        'Kſ@example.com',
       ]);
     });
 

library/src/regex.ts

@@ -39,7 +39,8 @@ export const DOMAIN_REGEX: RegExp =
  * [Email address](https://en.wikipedia.org/wiki/Email_address) regex.
  */
 export const EMAIL_REGEX: RegExp =
-  /^[\w+-]+(?:\.[\w+-]+)*@[\da-z]+(?:[.-][\da-z]+)*\.[a-z]{2,}$/iu;
+  // eslint-disable-next-line regexp/require-unicode-regexp, redos-detector/no-unsafe-regex -- false positive (recheck playground says this is safe). Intentionally omit /u because /iu makes \w match some non-ASCII chars via Unicode case-folding (e.g. K, ſ).
+  /^[\w+-]+(?:\.[\w+-]+)*@[\da-z]+(?:[.-][\da-z]+)*\.[a-z]{2,}$/i;
 
 /**
  * Emoji regex from [emoji-regex-xs](https://github.com/slevithan/emoji-regex-xs) v1.0.0 (MIT license).