[Security] Disabled the BCryptPasswordEncoder tests for PHP < 5.3.7

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #7994
| License       | MIT
| Doc PR        | -

See https://github.com/ircmaxell/password_compat/issues/10#issuecomment-11203833.