refactor: replace deprecated String.prototype.substr() (#1066)

.substr() is deprecated so we replace it with .slice() which works similarily but isn't deprecated

Signed-off-by: Tobias Speicher <[email protected]>

Co-authored-by: Daniel Lee <[email protected]>

Author: CommanderRoot

src/common/providers/https.ts

@@ -437,7 +437,7 @@ function isValidRequest(req: Request): req is HttpRequest {
   // If it has a charset, just ignore it for now.
   const semiColon = contentType.indexOf(';');
   if (semiColon >= 0) {
-    contentType = contentType.substr(0, semiColon).trim();
+    contentType = contentType.slice(0, semiColon).trim();
   }
   if (contentType !== 'application/json') {
     logger.warn('Request has incorrect Content-Type.', contentType);