ci: fix deb desktop entry

[ghost]

• The version key does not represent the version of the application, but rather the version of the desktop entry specification that the file follows. The version field is not required.
• The GenericName key is the generic name of the application, such as "Web Browser".
• If the Icon key is an absolute path, the given file will be used. If the path is not an absolute path, it should not have a suffix.
• Flutter_to_debian adds another Exec and Icon properties to the .desktop file even if there are already Exec and Icon.
• By the way: If it seems more standardized for the application's parent directory to use the default /opt than /usr/local/bin, you can use postinst to link /opt/gopeed/gopeed to /usr/bin/gopeed. Flutter_to_debian supports postinst.

[monkeyWie]

This information is very useful to me, tks~