Tiny fix for test number display

$ ./tools/osx/deploy_ci_agent.sh --tests
    PYTHON_DRIVE_VERSION = 3.9.2
    WORKSPACE            = /Users/tiger-222/projects
    WORKSPACE_DRIVE      = /Users/tiger-222/projects/nuxeo-drive
    STORAGE_DIR          = /Users/tiger-222/projects/deploy-dir
>>> [pyenv] Initializing
>>> [pyenv] Using Python 3.9.2
>>> Verifying Python version in use
>>> Checking Python code: import sqlite3 ... OK.
>>> Launching synchronization functional tests, file by file
    (first, run for each test file, failures are ignored to have
     a whole picture of errors)

>>> [1/      47] Testing tests/old_functional/test_special_characters.py ...
bringing up nodes...
# ...