tests/scap/test_cli.py: Fix test_announce

Some future code that I will be adding to announce() will generate a
warning if the number of supplied parameters does not match the number
expected by the format string. I changed a test call to announce()
which was passing a parameter that was not accessed by the format
string.

Before:

app.announce("test", "bar")  

After:

app.announce("test %s", "bar")