Updated "Bad credentials" translation source to "Bad credentials."

Updated "Bad credentials" translation source to "Bad credentials." in order to track [this update](https://github.com/symfony/symfony/pull/11215).

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | yes
| Deprecations? | no
| Tests pass?   | yes