refactor: change deprecated autocompletion to shell_complete

Before this fix, we sometimes got this warning running unit tests:
.../envs/ev-py310/lib/python3.10/site-packages/typer/core.py:304: DeprecationWarning: 'autocompletion' is renamed to 'sh>
  _typer_param_setup_autocompletion_compat(self, autocompletion=autocompletion)

Also, the click documentation confirms autocompletion is deprecated:
https://click.palletsprojects.com/en/stable/changes/#version-8-0-0

fs2/cli/benchmark.py

@@ -18,7 +18,7 @@ def benchmark(
         dir_okay=False,
         file_okay=True,
         help="The path to your model configuration file.",
-        autocompletion=complete_path,
+        shell_complete=complete_path,
     ),
     benchmark_type: BenchmarkType = BenchmarkType.training,
     gpu: bool = True,

fs2/cli/synthesize.py

@@ -282,7 +282,7 @@ def synthesize(  # noqa: C901
         exists=True,
         dir_okay=False,
         help="The path to a trained text-to-spec (i.e., feature prediction) or e2e EveryVoice model.",
-        autocompletion=complete_path,
+        shell_complete=complete_path,
     ),
     output_dir: Path = typer.Option(
         "synthesis_output",
@@ -291,7 +291,7 @@ def synthesize(  # noqa: C901
         file_okay=False,
         dir_okay=True,
         help="The directory where your synthesized audio should be written",
-        autocompletion=complete_path,
+        shell_complete=complete_path,
     ),
     texts: list[str] = typer.Option(
         [],
@@ -330,7 +330,7 @@ def synthesize(  # noqa: C901
         file_okay=True,
         dir_okay=False,
         help="The path to a file containing a list of utterances (a.k.a filelist). Use --text if you want to just synthesize one sample.",
-        autocompletion=complete_path,
+        shell_complete=complete_path,
     ),
     text_representation: DatasetTextRepresentation = typer.Option(
         DatasetTextRepresentation.characters,
@@ -354,7 +354,7 @@ def synthesize(  # noqa: C901
         help="ADVANCED. The path to preprocessed folder containing spec and duration folders to use for teacher-forcing the synthesized outputs.",
         dir_okay=True,
         file_okay=False,
-        autocompletion=complete_path,
+        shell_complete=complete_path,
     ),
     vocoder_path: Path = typer.Option(
         None,
@@ -363,7 +363,7 @@ def synthesize(  # noqa: C901
         help="The path to a trained vocoder (aka spec-to-wav model).",
         dir_okay=False,
         file_okay=True,
-        autocompletion=complete_path,
+        shell_complete=complete_path,
     ),
     batch_size: int = typer.Option(
         4,