Fix UnicodeEncodeError by ensuring UTF-8 encoding for file writes

[trunksn1]

his pull request addresses an issue encountered when using the Grasp extension with non-English characters. Specifically, an error (UnicodeEncodeError) occurred when attempting to write characters that are not supported by the default encoding on Windows (cp1252).

Changes Made: Updated the append_org function in the main.py file to explicitly use UTF-8 encoding when writing to the .org file. Reason for Change: Using UTF-8 encoding ensures that the application can handle a broader range of characters, including Greek letters and other non-ASCII characters. This enhancement improves the usability of the extension for users who work with scientific articles containing diverse character sets.

How to Test: Capture a note with non-English characters (e.g., Greek letters like "α-actinin"). Verify that the note is written to the .org file without any errors.