detect/byte_test: suppress scan-build warning

detect-bytetest.c:523:14: warning: 2nd function call argument is an uninitialized value [core.CallAndMessage]
  523 |         if (!DetectBytetestValidateNbytes(data, nbytes, optstr)) {
      |              ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1 warning generated.

src/detect-bytetest.c

@@ -324,7 +324,7 @@ static DetectBytetestData *DetectBytetestParse(
     int res = 0;
     size_t pcre2_len;
     int i;
-    uint32_t nbytes;
+    uint32_t nbytes = 0;
     const char *str_ptr = NULL;
     pcre2_match_data *match = NULL;