Key "MimeType" is a list and needs a semicolon as trailing character

https://specifications.freedesktop.org/desktop-entry-spec/desktop-entry-spec-latest.html#mime-types

Author: probonopd

build/linux/dist/desktop.template

@@ -7,6 +7,6 @@ Exec=<BINARY_LOCATION>
 Icon=<ICON_NAME>
 Terminal=false
 Categories=Development;IDE;Electronics;
-MimeType=text/x-arduino
+MimeType=text/x-arduino;
 Keywords=embedded electronics;electronics;avr;microcontroller;
 StartupWMClass=processing-app-Base