Don't run flake8 as part of the basic tests

This script should only run tests to check that cheribuild still works
rather than also running the linting. This made sense when we didn't have
pre-commit enabled, but now pre-commit takes care of that.

tests/run_basic_tests.sh

@@ -12,9 +12,6 @@ try_run_verbose() {
  fi
 }
 
-# check for errors that would fail the GitHub CI:
-try_run_verbose python3 -m flake8
-
 # check that there are no obvious mistakes:
 sh "$SCRIPT_DIR/run_smoke_tests.sh"