Add python3 repo

twrp-extras.xml

@@ -21,6 +21,8 @@
 <!-- Include Magisk repo for resetprop support -->
     <project path="external/magisk-prebuilt" name="external_magisk-prebuilt" remote="TeamWin" revision="android-7.1" />
 
+    <project path="external/python3" name="android_external_python3" remote="TeamWin" revision="android-9.0"/>
+
 <!-- Include forked external unzip repo from CyanogenMod for toolbox/toybox support -->
     <project path="external/unzip" name="android_external_unzip" remote="TeamWin" revision="cm-14.1" />