Fix: Use FileNotFoundError for file not found in main.py

Replaced IOError with FileNotFoundError on line 377 of main.py to use a more specific and appropriate exception for file not found errors.

test: update test_find_dotenv_no_file_raise to expect FileNotFoundError
Updated test_main.py (line 351) to replace IOError with FileNotFoundError so that the test matches the updated exception handling in main.py.

Author: creepereye1204

tests/test_main.py

@@ -178,7 +178,8 @@ def test_get_key_no_file(tmp_path):
     assert result is None
     mock_info.assert_has_calls(
         calls=[
-            mock.call("python-dotenv could not find configuration file %s.", nx_path)
+            mock.call(
+                "python-dotenv could not find configuration file %s.", nx_path)
         ],
     )
     mock_warning.assert_has_calls(
@@ -193,7 +194,8 @@ def test_get_key_not_found(dotenv_path):
         result = dotenv.get_key(dotenv_path, "foo")
 
     assert result is None
-    mock_warning.assert_called_once_with("Key %s not found in %s.", "foo", dotenv_path)
+    mock_warning.assert_called_once_with(
+        "Key %s not found in %s.", "foo", dotenv_path)
 
 
 def test_get_key_ok(dotenv_path):
@@ -346,7 +348,7 @@ def test_find_dotenv_no_file_raise(tmp_path):
     leaf = prepare_file_hierarchy(tmp_path)
     os.chdir(leaf)
 
-    with pytest.raises(IOError):
+    with pytest.raises(FileNotFoundError):
         dotenv.find_dotenv(raise_error_if_not_found=True, usecwd=True)