style(editorconfig): update newline setting

The setting wasn't consistent with the one used in the Visual Studio
Code settings, which caused different newline formatting depending on
whether the user uses Visual Studio Code or another editor that uses
EditorConfig.

.editorconfig

@@ -1,7 +1,7 @@
 root = true
 
 [*]
-insert_final_newline = false
+insert_final_newline = true
 
 [{*.{c,cpp,cc,h,hpp},CMakeLists.txt,Kconfig}]
 indent_style = tab