[lldb] Emit type annotation in SWIG generated Python code.

The Python code generated by SWIG is compatible with both Python 2 and
Python 3. The -py3 option enables Python 2 incompatible features such as
function annotations and abstract base classes.

Differential revision: https://reviews.llvm.org/D96096

GitOrigin-RevId: e5228ef556e5a4cb40c6c7936aada636e1b7be10
diff --git a/bindings/python/CMakeLists.txt b/bindings/python/CMakeLists.txt
index baad7e8..2b14ee3 100644
--- a/bindings/python/CMakeLists.txt
+++ b/bindings/python/CMakeLists.txt
@@ -10,6 +10,7 @@
       -c++
       -shadow
       -python
+      -py3
       -threads
       -outdir ${CMAKE_CURRENT_BINARY_DIR}
       -o ${CMAKE_CURRENT_BINARY_DIR}/LLDBWrapPython.cpp