fix: reject non-digit characters in valid_cc_number()
#14426
| Job | Run time |
|---|---|
| 1m 11s | |
| 1m 5s | |
| 2m 16s |
valid_cc_number()
#14426
| Job | Run time |
|---|---|
| 1m 11s | |
| 1m 5s | |
| 2m 16s |