Remove python3_bbappend

This is not required anymore. The turtledemo were part of the
python3-misc package which is not used anymore.

BugzID: 81512

bbappends/core/recipes-devtools/python/python3_%.bbappend

@@ -1,5 +0,0 @@
-do_install_append(){
-    cd ${D}${libdir}/python${PYTHON_MAJMIN}
-    rm -rf turtle.py turtledemo/
-    cd -
-}