nixos/test-driver: show deprecation warnings in the REPL

Apparently this wasn't the case before, but now it is

    In [3]: machine.shell_interact()
    ??? Warning (DeprecationWarning): Use the SSH backdoor instead
        File "<ipython-input-3-4e72ea6a987e>", line 1

nixos/lib/test-driver/src/test_driver/__init__.py

@@ -6,6 +6,7 @@ import warnings
 from pathlib import Path
 
 import ptpython.ipython
+import ptpython.repl
 from colorama import Fore, Style
 
 from test_driver.debug import Debug, DebugAbstract, DebugNop
@@ -174,6 +175,7 @@ def main() -> None:
         if args.interactive:
             history_dir = os.getcwd()
             history_path = os.path.join(history_dir, ".nixos-test-history")
+            ptpython.repl.enable_deprecation_warnings()
             ptpython.ipython.embed(
                 user_ns=driver.test_symbols(),
                 history_filename=history_path,