Make entropy of mock API key more obvious

[skonves]

Currently, a randomly selected, hard-coded value is sent as an API key for testing mock routes that required authentication. This value should be obtained from an instance of Mocker or from a user-defined function.

rigorous/src/tester/utils/index.ts

Line 77 in ecb55cc

const value = '74tybcqo874tbyqo874t3';