refactor(Core): NULL -> nullptr (#3275)

* NULL to nullptr

* NULL to nullptr

* NULL to nullptr

* NULL to nullptr

* NULL to nullptr

Co-authored-by: Francesco Borzì <borzifrancesco@gmail.com>
Co-authored-by: Stefano Borzì <stefanoborzi32@gmail.com>

src/server/authserver/Server/TOTP.cpp

@@ -71,7 +71,7 @@ namespace TOTP
         memset(encoded, 0, bufsize);
         unsigned int hmacResSize = HMAC_RES_SIZE;
         unsigned char hmacRes[HMAC_RES_SIZE];
-        unsigned long timestamp = time(NULL)/30;
+        unsigned long timestamp = time(nullptr)/30;
         unsigned char challenge[8];
          for (int i = 8; i--;timestamp >>= 8)
             challenge[i] = timestamp;