test: address multipart version PR review feedback

Make the 0.0.100 regression test fail on master by removing multipart
fallback, and move _version_str_to_tuple tests to test_dependencies_utils.

tests/test_dependencies_utils.py

@@ -1,4 +1,11 @@
-from fastapi.dependencies.utils import get_typed_annotation
+from fastapi.dependencies.utils import _version_str_to_tuple, get_typed_annotation
+
+
+def test_version_str_to_tuple():
+    assert _version_str_to_tuple("0.0.12") == (0, 0, 12)
+    assert _version_str_to_tuple("0.0.100") == (0, 0, 100)
+    assert _version_str_to_tuple("1.2.3a1") == (1, 2, 3)
+    assert _version_str_to_tuple("") == ()
 
 
 def test_get_typed_annotation():

tests/test_multipart_installation.py

@@ -3,7 +3,6 @@ import warnings
 import pytest
 from fastapi import FastAPI, File, Form, UploadFile
 from fastapi.dependencies.utils import (
-    _version_str_to_tuple,
     multipart_incorrect_install_error,
     multipart_not_installed_error,
 )
@@ -154,15 +153,9 @@ def test_new_multipart_version_without_multipart_alias(monkeypatch):
     monkeypatch.setattr("python_multipart.__version__", "0.0.100")
     with warnings.catch_warnings(record=True):
         warnings.simplefilter("always")
+        monkeypatch.delattr("multipart.__version__", raising=False)
         app = FastAPI()
 
         @app.post("/")
         async def root(username: str = Form()):
             return username  # pragma: nocover
-
-
-def test_version_str_to_tuple():
-    assert _version_str_to_tuple("0.0.12") == (0, 0, 12)
-    assert _version_str_to_tuple("0.0.100") == (0, 0, 100)
-    assert _version_str_to_tuple("1.2.3a1") == (1, 2, 3)
-    assert _version_str_to_tuple("") == ()