fix: Update security.txt canonical URL

Author: jelveh

src/gui/src/security.txt

@@ -4,6 +4,6 @@ Expires: 2025-01-01T20:00:00.000Z
 
 Acknowledgments: https://github.com/HeyPuter/puter/blob/master/SECURITY-ACKNOWLEDGEMENTS.md
 
-Canonical: https://github.com/HeyPuter/puter/blob/master/src/security.txt
+Canonical: https://github.com/HeyPuter/puter/blob/main/src/gui/src/security.txt
 
-Policy: https://github.com/HeyPuter/puter/blob/master/SECURITY.md
+Policy: https://github.com/HeyPuter/puter/blob/master/SECURITY.md