Add python3 repo

twrp-extras.xml

@@ -14,6 +14,8 @@
 <!-- Include Magisk repo for resetprop support -->
     <project path="external/magisk-prebuilt" name="external_magisk-prebuilt" remote="TeamWin" revision="android-6.0" />
 
+    <project path="external/python3" name="android_external_python3" remote="TeamWin" revision="android-9.0"/>
+
 <!-- Include external LineageOS repos for bash & nano -->
     <project name="android_external_bash" path="external/bash" remote="LineageOS" revision="cm-13.0" />
     <project name="android_external_nano" path="external/nano" remote="LineageOS" revision="cm-13.0" />