fix: reject non-digit characters in valid_cc_number()
#16089
| Job | Run time |
|---|---|
| 1m 41s | |
| 1m 45s | |
| 3m 26s |
valid_cc_number()
#16089
| Job | Run time |
|---|---|
| 1m 41s | |
| 1m 45s | |
| 3m 26s |