Use constant time equality check for auth token

[pethin]

Replace === with crypto.subtle.timingSafeEqual in https://github.com/Sh4yy/cloudflare-email/blob/main/src/middlewares/auth.ts#L16 to prevent timing attacks.

Example: https://developers.cloudflare.com/workers/examples/protect-against-timing-attacks/

[D3vl0per]

Like this @pethin https://github.com/D3vl0per/cloudflare-email/blob/main/src/middlewares/auth.ts?

[taciturnaxolotl]

Can you create a PR @D3vl0per?

[D3vl0per]

Done #18 @kcoderhtml !

[taciturnaxolotl]

thnks! hopefully @Sh4yy can merge both our PRs soon!