tests/psh: `history` test code not amended after issue close

[niewim19]

In tests/psh/history.py there is a commented test with referenced issue. The issue is already solved and test case is still commented.

Testcase:

• https://github.com/phoenix-rtos/phoenix-rtos-tests/blob/c68dd2fed4e468dfbcdcabe08059b3e1893b90c5/psh/test-history.py#L29-L32

Referenced issue:

• https://github.com/phoenix-rtos/phoenix-rtos-project/issues/521

[damianloew]

Done