docs: update Python version screenshot and text for Custom Python

- Python 3.14 is now the recommended choice (was 3.13)
- Removed 'release candidate' label from Python 3.14
- Updated screenshot to reflect current UI

Co-Authored-By: martin.struzsky <martin@struzsky.cz>

Author: devin-ai-integration[bot]

components/applications/custom-python/custom-python-1.png

@@ -40,8 +40,8 @@ all without leaving Keboola.
 
 Select the Python version for your code:
 
-- **3.13** *(recommended)* — Isolated environment with only the packages you install.
-- **3.14** — Isolated environment (release candidate).
+- **3.14** *(recommended)* — Isolated environment with only the packages you install.
+- **3.13** — Isolated environment.
 - **3.12** — Isolated environment.
 - **base** — Shared environment (Python 3.10) with many pre-installed packages in legacy versions. Not recommended; will be deprecated in the future.