RuntimeError when saving image with filename missing or not expected an extension

[FRiMN]

When saving an image via the menu, if a filename is specified without an expected extension (e.g., .jpg, .png, etc.), the application raises a RuntimeError stating it cannot open the file.

Traceback (most recent call last):
  File "/home/frimn/genui/src/genui/ui_widgets/photo_viewer.py", line 183, in save_image_manual
    self.save_image(file_name)
  File "/home/frimn/genui/src/genui/ui_widgets/photo_viewer.py", line 191, in save_image
    self._save_metadata_to_image(file_path)
  File "/home/frimn/genui/src/genui/ui_widgets/photo_viewer.py", line 197, in _save_metadata_to_image
    with pyexiv2.Image(str(file_path)) as img:
  File "/home/frimn/genui/.venv/lib/python3.10/site-packages/pyexiv2/core.py", line 14, in __init__
    self._exiv2api_image = exiv2api.Image(filename.encode(encoding))
RuntimeError: /home/frimn/test: Failed to open the data source: Нет такого файла или каталога (errno = 2)

Steps to Reproduce:

1. Open an image in the application.
2. Select "Save Image" from the right-click menu.
3. In the save dialog, enter a filename with unexpected or without an extension (e.g., test or test.gif instead of test.jpg).
4. Click "Save."